<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2023 Workiva-->
<!--r:296ef596-d060-4773-a69d-e8dd7a63d0eb,g:1ab7a8a1-bbe9-417b-ae7a-979e68033532-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.suncountry.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="sncy-20221231.xsd#CONSOLIDATEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="extended" id="iab30608ac4d447ff857f46f10dd3380f_CONSOLIDATEDBALANCESHEETS">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_4410812f-7500-4a2d-a388-040ee969276e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_94c58d72-d5bf-4523-8284-f4ad0024249b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4410812f-7500-4a2d-a388-040ee969276e" xlink:to="loc_us-gaap_AssetsAbstract_94c58d72-d5bf-4523-8284-f4ad0024249b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_94c58d72-d5bf-4523-8284-f4ad0024249b" xlink:to="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_60341d60-0af7-4a68-baf5-46862ab79515" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_60341d60-0af7-4a68-baf5-46862ab79515" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_3004eed4-00ec-4119-b133-ea48df565bef" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_RestrictedCashCurrent_3004eed4-00ec-4119-b133-ea48df565bef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_944afb30-e942-4d7c-abb0-f15fe572ce2e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_ShortTermInvestments_944afb30-e942-4d7c-abb0-f15fe572ce2e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_fb47facb-0369-4642-abd0-9035fd9dfe28" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_fb47facb-0369-4642-abd0-9035fd9dfe28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsAssetsCurrent_29ffb7b6-eba1-46c3-b35e-0f5eff642f4e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DepositsAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_DepositsAssetsCurrent_29ffb7b6-eba1-46c3-b35e-0f5eff642f4e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_798abb10-1399-4b7b-81f9-c744964a71ac" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_InventoryNet_798abb10-1399-4b7b-81f9-c744964a71ac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseCurrent_be945159-f123-4a17-9da5-6f1ab40af2ce" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PrepaidExpenseCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_PrepaidExpenseCurrent_be945159-f123-4a17-9da5-6f1ab40af2ce" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent_7692be67-5d34-4a74-9ae9-929ccf3a5dbe" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_OtherAssetsCurrent_7692be67-5d34-4a74-9ae9-929ccf3a5dbe" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_4a1ca7f6-f8b9-4a70-a5b0-743be15b06d7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_5fc3ba55-cc7e-4722-945c-fe6014311bea" xlink:to="loc_us-gaap_AssetsCurrent_4a1ca7f6-f8b9-4a70-a5b0-743be15b06d7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_87843fcb-d7c0-4a6c-9bb1-2345811d75a2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_94c58d72-d5bf-4523-8284-f4ad0024249b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_87843fcb-d7c0-4a6c-9bb1-2345811d75a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_f61f0282-f134-44b1-9616-e36f09f9e825" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_87843fcb-d7c0-4a6c-9bb1-2345811d75a2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_f61f0282-f134-44b1-9616-e36f09f9e825" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_a666fed5-8969-40ae-a9de-9b11c9919b0c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_87843fcb-d7c0-4a6c-9bb1-2345811d75a2" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_a666fed5-8969-40ae-a9de-9b11c9919b0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_e6688cfb-35f1-428c-b084-3a49531b42a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_87843fcb-d7c0-4a6c-9bb1-2345811d75a2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_e6688cfb-35f1-428c-b084-3a49531b42a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_b9267ca4-d53e-4d5a-8633-534b7114a7ef" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_87843fcb-d7c0-4a6c-9bb1-2345811d75a2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_b9267ca4-d53e-4d5a-8633-534b7114a7ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_0e54ef80-9ab8-4114-9f7c-635c6fec2d49" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_87843fcb-d7c0-4a6c-9bb1-2345811d75a2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_0e54ef80-9ab8-4114-9f7c-635c6fec2d49" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_94c58d72-d5bf-4523-8284-f4ad0024249b" xlink:to="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_f2f4a789-0a76-4b4d-b444-7d3d806015ed" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_us-gaap_Goodwill_f2f4a789-0a76-4b4d-b444-7d3d806015ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_eb466e4c-4048-4d96-ae7e-5ca78075f662" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_eb466e4c-4048-4d96-ae7e-5ca78075f662" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_dce95aed-27e1-4718-a9f5-aabb51e3ad18" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_dce95aed-27e1-4718-a9f5-aabb51e3ad18" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftLeaseDeposits_2b1717c8-7dac-4b21-9531-30a45f291a48" xlink:href="sncy-20221231.xsd#sncy_AircraftLeaseDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_sncy_AircraftLeaseDeposits_2b1717c8-7dac-4b21-9531-30a45f291a48" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsAssetsNoncurrent_bac936c0-8a8e-4a52-b7a5-618d70aaf07d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DepositsAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_us-gaap_DepositsAssetsNoncurrent_bac936c0-8a8e-4a52-b7a5-618d70aaf07d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_eb20d9d6-8120-4dec-aeea-1004f96c42f5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_eb20d9d6-8120-4dec-aeea-1004f96c42f5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_21c72197-6eee-43a8-aa51-a9fb9ddbadfe" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_21c72197-6eee-43a8-aa51-a9fb9ddbadfe" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_6ff709fe-9c57-4421-9353-4635176a8a3c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_fe6ce8ab-27b5-484d-abf4-8297a17f1ee2" xlink:to="loc_us-gaap_OtherAssets_6ff709fe-9c57-4421-9353-4635176a8a3c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_84b77166-0401-4be2-93c5-3c441f4ca087" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_94c58d72-d5bf-4523-8284-f4ad0024249b" xlink:to="loc_us-gaap_Assets_84b77166-0401-4be2-93c5-3c441f4ca087" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4410812f-7500-4a2d-a388-040ee969276e" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_e032278b-54a8-4976-b79a-34155452d811" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_AccountsPayableCurrent_e032278b-54a8-4976-b79a-34155452d811" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_d9ab4c3a-7b23-469a-94d2-220f1da8f3bf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_d9ab4c3a-7b23-469a-94d2-220f1da8f3bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccrualForTaxesOtherThanIncomeTaxesCurrent_77106f1b-f559-4f8e-b1c3-48b5a4212a87" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccrualForTaxesOtherThanIncomeTaxesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_AccrualForTaxesOtherThanIncomeTaxesCurrent_77106f1b-f559-4f8e-b1c3-48b5a4212a87" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AirTrafficLiabilitiesCurrent_62cc20ae-abf4-4597-9882-757ae1ef4f3e" xlink:href="sncy-20221231.xsd#sncy_AirTrafficLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_sncy_AirTrafficLiabilitiesCurrent_62cc20ae-abf4-4597-9882-757ae1ef4f3e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OvermarketLiabilitiesCurrent_ae6edb68-5d25-4d52-9f99-5ef5927e23f6" xlink:href="sncy-20221231.xsd#sncy_OvermarketLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_sncy_OvermarketLiabilitiesCurrent_ae6edb68-5d25-4d52-9f99-5ef5927e23f6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_edaafc07-e01c-4a67-903d-d025a695fee1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_edaafc07-e01c-4a67-903d-d025a695fee1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_LoyaltyProgramLiabilitiesCurrent_b2e11046-cfa3-4f1d-ad8a-5c608a63e8f1" xlink:href="sncy-20221231.xsd#sncy_LoyaltyProgramLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_sncy_LoyaltyProgramLiabilitiesCurrent_b2e11046-cfa3-4f1d-ad8a-5c608a63e8f1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_4e7a62a6-ef8c-4288-9a72-797589d7e820" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_4e7a62a6-ef8c-4288-9a72-797589d7e820" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_d18ab2cd-6218-4374-9743-e9e68f4282f1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_LongTermDebtCurrent_d18ab2cd-6218-4374-9743-e9e68f4282f1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_IncomeTaxesReceivableAgreementCurrent_e6a02344-d801-480c-be84-c8d5e628410f" xlink:href="sncy-20221231.xsd#sncy_IncomeTaxesReceivableAgreementCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_sncy_IncomeTaxesReceivableAgreementCurrent_e6a02344-d801-480c-be84-c8d5e628410f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_80aefa02-d5fc-4bd6-acf0-67893ea45be5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_80aefa02-d5fc-4bd6-acf0-67893ea45be5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_e57e2bd6-5a76-433b-b097-ccb99e752ccb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_592f110d-a871-4b04-961f-67db1c95fa79" xlink:to="loc_us-gaap_LiabilitiesCurrent_e57e2bd6-5a76-433b-b097-ccb99e752ccb" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:to="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OvermarketLiabilitiesNoncurrent_df59c241-a10c-474a-b8e6-0465f33cd87b" xlink:href="sncy-20221231.xsd#sncy_OvermarketLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_sncy_OvermarketLiabilitiesNoncurrent_df59c241-a10c-474a-b8e6-0465f33cd87b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_77ef47dd-d382-4571-aa28-ba2135208156" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_77ef47dd-d382-4571-aa28-ba2135208156" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_LoyaltyProgramLiabilitiesNoncurrent_01ac7f55-79fd-427e-bd8b-e065fa06160b" xlink:href="sncy-20221231.xsd#sncy_LoyaltyProgramLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_sncy_LoyaltyProgramLiabilitiesNoncurrent_01ac7f55-79fd-427e-bd8b-e065fa06160b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_39820e74-c8f3-487a-961f-5aee3d1f7e37" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_39820e74-c8f3-487a-961f-5aee3d1f7e37" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_92fe3f1d-baa3-496e-9ad8-822111d7aabd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_92fe3f1d-baa3-496e-9ad8-822111d7aabd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_IncomeTaxesReceivableAgreementNoncurrent_0b255834-65b4-45d4-b870-836ad987f1c0" xlink:href="sncy-20221231.xsd#sncy_IncomeTaxesReceivableAgreementNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_sncy_IncomeTaxesReceivableAgreementNoncurrent_0b255834-65b4-45d4-b870-836ad987f1c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_a7fcd22f-6d96-4627-9c06-c4c0ba391c8b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_a7fcd22f-6d96-4627-9c06-c4c0ba391c8b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrent_0cae5b78-555b-410a-8ce8-51dec8027389" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_6fc7fc11-d45e-422e-aef3-58cae1a35da3" xlink:to="loc_us-gaap_LiabilitiesNoncurrent_0cae5b78-555b-410a-8ce8-51dec8027389" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_820cae42-8b60-4c33-9adf-525c4c51fa50" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:to="loc_us-gaap_Liabilities_820cae42-8b60-4c33-9adf-525c4c51fa50" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_f95899db-b975-4635-aa38-40fe364af1a8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:to="loc_us-gaap_CommitmentsAndContingencies_f95899db-b975-4635-aa38-40fe364af1a8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_ab2f4d81-a29a-4a4d-a0a3-031bcf342731" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:to="loc_us-gaap_CommonStockValue_ab2f4d81-a29a-4a4d-a0a3-031bcf342731" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_066c9f44-5523-459f-9449-d8ded4e7319d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:to="loc_us-gaap_PreferredStockValue_066c9f44-5523-459f-9449-d8ded4e7319d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValue_b5febe77-aea6-42b3-9be2-6a6fdd9a43dc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:to="loc_us-gaap_TreasuryStockValue_b5febe77-aea6-42b3-9be2-6a6fdd9a43dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_e36dba94-24d2-4690-886b-3cd009af49ca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:to="loc_us-gaap_AdditionalPaidInCapital_e36dba94-24d2-4690-886b-3cd009af49ca" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_ca06fd33-5fde-42f6-8255-723d633467c2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_ca06fd33-5fde-42f6-8255-723d633467c2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_a039eaa4-01ec-4fb2-b47d-7a14bc0d139a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_a039eaa4-01ec-4fb2-b47d-7a14bc0d139a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_7eed38f3-1bdb-4009-a726-aa69a1f0ab74" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_380852f6-6f0c-46ca-8474-aa90f8c9de79" xlink:to="loc_us-gaap_StockholdersEquity_7eed38f3-1bdb-4009-a726-aa69a1f0ab74" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_5b9663fe-d8b6-4ad8-855d-645449665292" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_580a088f-95c5-472a-96e9-6048fcc91ad6" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_5b9663fe-d8b6-4ad8-855d-645449665292" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_0a090a6a-e173-47bf-97ff-ff07751fa538" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_4410812f-7500-4a2d-a388-040ee969276e" xlink:to="loc_us-gaap_StatementTable_0a090a6a-e173-47bf-97ff-ff07751fa538" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5f619987-2b94-4a66-a1a7-3b1d161c05dd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_0a090a6a-e173-47bf-97ff-ff07751fa538" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5f619987-2b94-4a66-a1a7-3b1d161c05dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5f619987-2b94-4a66-a1a7-3b1d161c05dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5f619987-2b94-4a66-a1a7-3b1d161c05dd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5f619987-2b94-4a66-a1a7-3b1d161c05dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ba5cf83f-d66b-40a8-b1eb-1aa019229d67" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5f619987-2b94-4a66-a1a7-3b1d161c05dd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ba5cf83f-d66b-40a8-b1eb-1aa019229d67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AirTransportationEquipmentMember_529032c4-5a42-4f1a-97de-a1d131def511" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AirTransportationEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ba5cf83f-d66b-40a8-b1eb-1aa019229d67" xlink:to="loc_us-gaap_AirTransportationEquipmentMember_529032c4-5a42-4f1a-97de-a1d131def511" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_e98fa272-f24c-40dc-8a12-0d5f139e1f3c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ba5cf83f-d66b-40a8-b1eb-1aa019229d67" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_e98fa272-f24c-40dc-8a12-0d5f139e1f3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_a9c46caa-0a03-4691-892b-ea4dd3845af6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ba5cf83f-d66b-40a8-b1eb-1aa019229d67" xlink:to="loc_us-gaap_ComputerEquipmentMember_a9c46caa-0a03-4691-892b-ea4dd3845af6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftsUnderFinanceLeasesMember_431d6ced-0aee-4262-bc60-8cc5687ed797" xlink:href="sncy-20221231.xsd#sncy_AircraftsUnderFinanceLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ba5cf83f-d66b-40a8-b1eb-1aa019229d67" xlink:to="loc_sncy_AircraftsUnderFinanceLeasesMember_431d6ced-0aee-4262-bc60-8cc5687ed797" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_RotablePartsMember_3396fffe-d7ca-4c20-8363-8c68dc7d34ea" xlink:href="sncy-20221231.xsd#sncy_RotablePartsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ba5cf83f-d66b-40a8-b1eb-1aa019229d67" xlink:to="loc_sncy_RotablePartsMember_3396fffe-d7ca-4c20-8363-8c68dc7d34ea" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="sncy-20221231.xsd#CONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended" id="i5bd96d6ca55446dc9930639af649d39e_CONSOLIDATEDSTATEMENTSOFOPERATIONS">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_48b1792c-3e46-41e0-94e5-560769cc56c4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_RevenuesAbstract_48b1792c-3e46-41e0-94e5-560769cc56c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_37376db8-ec50-40b1-b203-220be3b03ae2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_48b1792c-3e46-41e0-94e5-560769cc56c4" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_37376db8-ec50-40b1-b203-220be3b03ae2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FuelCosts_f3a03fa1-fa88-4d18-8542-b93a0ac2dc5a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FuelCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_FuelCosts_f3a03fa1-fa88-4d18-8542-b93a0ac2dc5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_deb898a7-5c02-414d-a716-31fadef8db52" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_LaborAndRelatedExpense_deb898a7-5c02-414d-a716-31fadef8db52" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AircraftRental_93f93eb6-ce83-4353-9461-36c8b60da80c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AircraftRental"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_AircraftRental_93f93eb6-ce83-4353-9461-36c8b60da80c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AircraftMaintenanceMaterialsAndRepairs_9805c54d-f1f7-4cfb-96be-7afea4235edd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AircraftMaintenanceMaterialsAndRepairs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_AircraftMaintenanceMaterialsAndRepairs_9805c54d-f1f7-4cfb-96be-7afea4235edd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_05da3ac0-2dee-4b15-be8b-df69cbb85b7b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_SellingAndMarketingExpense_05da3ac0-2dee-4b15-be8b-df69cbb85b7b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_ab5e7549-bd31-46e0-b679-77cea2457a48" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_ab5e7549-bd31-46e0-b679-77cea2457a48" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_GroundHandlingExpense_2e9a8b6c-fe20-4ac3-8438-a6107b12b8ff" xlink:href="sncy-20221231.xsd#sncy_GroundHandlingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_sncy_GroundHandlingExpense_2e9a8b6c-fe20-4ac3-8438-a6107b12b8ff" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandingFeesAndOtherRentals_962db72d-fa5e-4d12-820b-71c85055ed24" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LandingFeesAndOtherRentals"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_LandingFeesAndOtherRentals_962db72d-fa5e-4d12-820b-71c85055ed24" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemNetGainLoss_d8635ead-f082-4eb5-9074-97e8dbada50b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemNetGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_UnusualOrInfrequentItemNetGainLoss_d8635ead-f082-4eb5-9074-97e8dbada50b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_45402603-abf2-4639-a318-e1159b809d74" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_45402603-abf2-4639-a318-e1159b809d74" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_6fcc1d82-ec28-4c82-9ab6-802c337e42ba" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_53861172-4c3b-450c-afd1-f008ed610ee8" xlink:to="loc_us-gaap_CostsAndExpenses_6fcc1d82-ec28-4c82-9ab6-802c337e42ba" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_62672b07-e738-4a76-8a1e-5464250aa450" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_OperatingIncomeLoss_62672b07-e738-4a76-8a1e-5464250aa450" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_8273398f-039f-4b87-9a06-41634a125449" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_8273398f-039f-4b87-9a06-41634a125449" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_bb662be9-5873-4e5b-9798-8793dab578a0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_8273398f-039f-4b87-9a06-41634a125449" xlink:to="loc_us-gaap_InvestmentIncomeInterest_bb662be9-5873-4e5b-9798-8793dab578a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_ac426a86-725e-4e4e-8dda-08d872f760cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_8273398f-039f-4b87-9a06-41634a125449" xlink:to="loc_us-gaap_InterestExpense_ac426a86-725e-4e4e-8dda-08d872f760cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_b64437fc-1f29-44a1-8c92-39f2ccf37519" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_8273398f-039f-4b87-9a06-41634a125449" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_b64437fc-1f29-44a1-8c92-39f2ccf37519" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_c97f75f8-f620-4636-8d03-4d5af7904cd9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_8273398f-039f-4b87-9a06-41634a125449" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_c97f75f8-f620-4636-8d03-4d5af7904cd9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_f4f86afd-c9df-4ec3-b72e-f5ffff62ff0c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_f4f86afd-c9df-4ec3-b72e-f5ffff62ff0c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_69357d82-72f9-494a-a93c-f5c320b3eeba" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_69357d82-72f9-494a-a93c-f5c320b3eeba" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_77ef4626-ab2f-47de-b9bc-46b290d891e9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_NetIncomeLoss_77ef4626-ab2f-47de-b9bc-46b290d891e9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_57968fcd-c4d2-48f9-9743-469f79b84fb6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_EarningsPerShareReconciliationAbstract_57968fcd-c4d2-48f9-9743-469f79b84fb6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_a466f004-a28e-4a4c-ab87-1c8713ba148a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_57968fcd-c4d2-48f9-9743-469f79b84fb6" xlink:to="loc_us-gaap_EarningsPerShareBasic_a466f004-a28e-4a4c-ab87-1c8713ba148a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_d63807de-f3e1-4ee9-9bfe-d05f4b4c3bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_57968fcd-c4d2-48f9-9743-469f79b84fb6" xlink:to="loc_us-gaap_EarningsPerShareDiluted_d63807de-f3e1-4ee9-9bfe-d05f4b4c3bf1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_00a96480-8163-4c77-9356-65e299a1b60c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_00a96480-8163-4c77-9356-65e299a1b60c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_7d1a510e-b826-4e35-aa95-3aed5b0da435" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_00a96480-8163-4c77-9356-65e299a1b60c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_7d1a510e-b826-4e35-aa95-3aed5b0da435" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_e9886378-cf0f-4c5b-a767-2960921135a8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_00a96480-8163-4c77-9356-65e299a1b60c" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_e9886378-cf0f-4c5b-a767-2960921135a8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_ed08fd75-4d50-4b65-82af-8a7fdb6f843e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_fd08e0c2-0f54-4303-ade5-4708df851143" xlink:to="loc_us-gaap_StatementTable_ed08fd75-4d50-4b65-82af-8a7fdb6f843e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_7c335687-95e0-4ed6-8da1-5d547163cd35" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ed08fd75-4d50-4b65-82af-8a7fdb6f843e" xlink:to="loc_srt_ProductOrServiceAxis_7c335687-95e0-4ed6-8da1-5d547163cd35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_7c335687-95e0-4ed6-8da1-5d547163cd35_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_7c335687-95e0-4ed6-8da1-5d547163cd35" xlink:to="loc_srt_ProductsAndServicesDomain_7c335687-95e0-4ed6-8da1-5d547163cd35_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_75a69d9a-e9b7-4557-9b70-884bafe97141" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_7c335687-95e0-4ed6-8da1-5d547163cd35" xlink:to="loc_srt_ProductsAndServicesDomain_75a69d9a-e9b7-4557-9b70-884bafe97141" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassengerMember_97c3b311-9e7e-454c-b708-65bc931450b9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PassengerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_75a69d9a-e9b7-4557-9b70-884bafe97141" xlink:to="loc_us-gaap_PassengerMember_97c3b311-9e7e-454c-b708-65bc931450b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CargoAndFreightMember_69ab9f82-dec6-4929-bfe2-762779253130" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CargoAndFreightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_75a69d9a-e9b7-4557-9b70-884bafe97141" xlink:to="loc_us-gaap_CargoAndFreightMember_69ab9f82-dec6-4929-bfe2-762779253130" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceOtherMember_9c4ee8a1-ec05-486d-8d0c-a3b6d79d2ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ServiceOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_75a69d9a-e9b7-4557-9b70-884bafe97141" xlink:to="loc_us-gaap_ServiceOtherMember_9c4ee8a1-ec05-486d-8d0c-a3b6d79d2ce8" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="sncy-20221231.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY" xlink:type="extended" id="i22a2e66949b947338ce56ad3c47055b5_CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_0729d114-45bc-40d9-a57e-5744ee2bcb4b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0729d114-45bc-40d9-a57e-5744ee2bcb4b" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_868bcd7b-e97c-494f-97a0-38f8602f56de" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_SharesOutstanding_868bcd7b-e97c-494f-97a0-38f8602f56de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_fad17b61-d8fd-4773-bd91-c05ee9e62bd4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockholdersEquity_fad17b61-d8fd-4773-bd91-c05ee9e62bd4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_f94329a8-9710-4ab4-860f-72000fd2279b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_TreasuryStockCommonShares_f94329a8-9710-4ab4-860f-72000fd2279b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsExercised_f8b5d973-1e9d-4d9f-adaf-8f88d8a481b7" xlink:href="sncy-20221231.xsd#sncy_WarrantsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_sncy_WarrantsExercised_f8b5d973-1e9d-4d9f-adaf-8f88d8a481b7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsExercisedValue_9379810b-6ee3-4c4e-8d43-252fd6af9fba" xlink:href="sncy-20221231.xsd#sncy_WarrantsExercisedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_sncy_WarrantsExercisedValue_9379810b-6ee3-4c4e-8d43-252fd6af9fba" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_58b01c09-79bc-43e2-beea-0aa1e92f677c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_NetIncomeLoss_58b01c09-79bc-43e2-beea-0aa1e92f677c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsIssued_61ac1483-aa45-4ac5-ab84-348fc8c2f7cc" xlink:href="sncy-20221231.xsd#sncy_WarrantsIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_sncy_WarrantsIssued_61ac1483-aa45-4ac5-ab84-348fc8c2f7cc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_6b5a9d3a-02b0-4397-ae71-115b81de7481" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_6b5a9d3a-02b0-4397-ae71-115b81de7481" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_af2a86a1-1ed7-4921-8c48-2fbb071c35a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_af2a86a1-1ed7-4921-8c48-2fbb071c35a3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_628cb0c9-5fc7-4d4a-8abb-38829409e3e6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_628cb0c9-5fc7-4d4a-8abb-38829409e3e6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_75247fab-4242-4f77-8a2c-e64df1283b50" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_75247fab-4242-4f77-8a2c-e64df1283b50" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_27c05efa-083d-462d-976b-799fef687b83" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_27c05efa-083d-462d-976b-799fef687b83" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_SharesSurrenderedByStockholdersSharesInExchangeOfPromissoryNotes_a8477b16-1d4e-4910-841e-6d56599b8e30" xlink:href="sncy-20221231.xsd#sncy_SharesSurrenderedByStockholdersSharesInExchangeOfPromissoryNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_sncy_SharesSurrenderedByStockholdersSharesInExchangeOfPromissoryNotes_a8477b16-1d4e-4910-841e-6d56599b8e30" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_SharesSurrenderedByStockholdersValueInExchangeOfPromissoryNotes_59121711-208c-4ccd-b3f8-3af22da363a8" xlink:href="sncy-20221231.xsd#sncy_SharesSurrenderedByStockholdersValueInExchangeOfPromissoryNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_sncy_SharesSurrenderedByStockholdersValueInExchangeOfPromissoryNotes_59121711-208c-4ccd-b3f8-3af22da363a8" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_08967cab-9037-4ef7-a309-b001c5718c81" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_08967cab-9037-4ef7-a309-b001c5718c81" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_f120ee4e-c545-42a5-86cb-d4425315c037" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_f120ee4e-c545-42a5-86cb-d4425315c037" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DecreaseInEquityDueToIncomeTaxReceivableAgreementLiability_73940ef0-e5a0-4fc2-b4fa-435377573074" xlink:href="sncy-20221231.xsd#sncy_DecreaseInEquityDueToIncomeTaxReceivableAgreementLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_sncy_DecreaseInEquityDueToIncomeTaxReceivableAgreementLiability_73940ef0-e5a0-4fc2-b4fa-435377573074" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_2b150926-dab2-4444-8127-f987b39aacaa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_2b150926-dab2-4444-8127-f987b39aacaa" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_0118b016-a417-47df-886c-39a417d19245" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_0118b016-a417-47df-886c-39a417d19245" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_f7de3209-bf1d-4156-ac31-f57bf5047d01" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_f7de3209-bf1d-4156-ac31-f57bf5047d01" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_6b3540e1-4b8d-4de3-8e33-82247e423a0a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_6b3540e1-4b8d-4de3-8e33-82247e423a0a" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_6e91e4b6-8ba2-4edd-80d8-ffbea16a3c91" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_6e91e4b6-8ba2-4edd-80d8-ffbea16a3c91" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_5167f7dd-11ca-4824-9713-dc0572b56e02" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_21c02355-8f44-494e-a89f-88531b035424" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_5167f7dd-11ca-4824-9713-dc0572b56e02" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_8d5259b4-75ac-4831-a176-d692668bc464" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_f53febd0-a1f1-4631-88b9-6384fcacad7d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_0076d1c0-b465-4773-b997-2fa7ced2dfb6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_e6a07452-7fc0-45a3-aa17-190620dfb7b9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0729d114-45bc-40d9-a57e-5744ee2bcb4b" xlink:to="loc_us-gaap_StatementTable_e6a07452-7fc0-45a3-aa17-190620dfb7b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_639cb7c2-161c-436c-81a2-4dde2146a323" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e6a07452-7fc0-45a3-aa17-190620dfb7b9" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_639cb7c2-161c-436c-81a2-4dde2146a323" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_639cb7c2-161c-436c-81a2-4dde2146a323_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_639cb7c2-161c-436c-81a2-4dde2146a323" xlink:to="loc_us-gaap_EquityComponentDomain_639cb7c2-161c-436c-81a2-4dde2146a323_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_639cb7c2-161c-436c-81a2-4dde2146a323" xlink:to="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_319f730e-dba3-4c09-b84d-6ddc9706286f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:to="loc_us-gaap_WarrantMember_319f730e-dba3-4c09-b84d-6ddc9706286f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_ec50ba46-9dc6-406f-ad81-90a409ea0823" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:to="loc_us-gaap_CommonStockMember_ec50ba46-9dc6-406f-ad81-90a409ea0823" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_942b8082-dc12-4410-8571-c9f4193b209a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:to="loc_us-gaap_TreasuryStockCommonMember_942b8082-dc12-4410-8571-c9f4193b209a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromStockholderMember_2fa2a3df-84db-4e52-9e73-7d601583c074" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReceivablesFromStockholderMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:to="loc_us-gaap_ReceivablesFromStockholderMember_2fa2a3df-84db-4e52-9e73-7d601583c074" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_d9b7e1b1-5998-4434-846f-572f78fd1cd4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_d9b7e1b1-5998-4434-846f-572f78fd1cd4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_9a82bff6-b7ec-4a52-a36a-2525805f4d6e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:to="loc_us-gaap_RetainedEarningsMember_9a82bff6-b7ec-4a52-a36a-2525805f4d6e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b5b94d79-4521-4ccc-9198-2dbbb01ec376" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4be576bf-b1b0-4e95-a00d-fa1ccd57c11a" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b5b94d79-4521-4ccc-9198-2dbbb01ec376" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/COMPANYBACKGROUNDDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#COMPANYBACKGROUNDDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/COMPANYBACKGROUNDDetails" xlink:type="extended" id="i0918e515f33a419e97f26211ceedf23f_COMPANYBACKGROUNDDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TermOfAgreement_9079be50-0317-4fa3-a2f4-02f8bc4f402d" xlink:href="sncy-20221231.xsd#sncy_TermOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_sncy_TermOfAgreement_9079be50-0317-4fa3-a2f4-02f8bc4f402d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfExtensionOptions_1a4279e1-f3be-440a-a84c-c506f1f6a8f5" xlink:href="sncy-20221231.xsd#sncy_NumberOfExtensionOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_sncy_NumberOfExtensionOptions_1a4279e1-f3be-440a-a84c-c506f1f6a8f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TermOfRenewalOfAgreement_0648f546-3574-4da2-919a-2622ed83b32f" xlink:href="sncy-20221231.xsd#sncy_TermOfRenewalOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_sncy_TermOfRenewalOfAgreement_0648f546-3574-4da2-919a-2622ed83b32f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ThresholdTermOfAgreement_8a651f6e-603d-4c38-9184-9df5ab8518cc" xlink:href="sncy-20221231.xsd#sncy_ThresholdTermOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_sncy_ThresholdTermOfAgreement_8a651f6e-603d-4c38-9184-9df5ab8518cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_9c0f8ec0-143b-48c9-bfa0-b415fab9823b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_9c0f8ec0-143b-48c9-bfa0-b415fab9823b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_02f308dc-17ce-4985-9660-d2ee2babeafa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_02f308dc-17ce-4985-9660-d2ee2babeafa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_a166c51e-ba70-4675-ae9e-6022b60cdc9c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_a166c51e-ba70-4675-ae9e-6022b60cdc9c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsVestedDuringPeriod_1b2e3d5f-5461-46bf-8dd0-53d72b1ad645" xlink:href="sncy-20221231.xsd#sncy_WarrantsVestedDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_sncy_WarrantsVestedDuringPeriod_1b2e3d5f-5461-46bf-8dd0-53d72b1ad645" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfWarrantsThatVestOnAchievementOfEachMilestone_3c38a08a-546d-404e-91a0-6d83a1a3091a" xlink:href="sncy-20221231.xsd#sncy_NumberOfWarrantsThatVestOnAchievementOfEachMilestone"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_sncy_NumberOfWarrantsThatVestOnAchievementOfEachMilestone_3c38a08a-546d-404e-91a0-6d83a1a3091a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantVestingConditionMilestoneAchievementQualifyingPaymentsReceivable_eb805ae0-908f-497c-a2fd-12701651b6c5" xlink:href="sncy-20221231.xsd#sncy_WarrantVestingConditionMilestoneAchievementQualifyingPaymentsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_sncy_WarrantVestingConditionMilestoneAchievementQualifyingPaymentsReceivable_eb805ae0-908f-497c-a2fd-12701651b6c5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_53cfb857-a1e6-42b9-bad9-eeb895c1f32f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_53cfb857-a1e6-42b9-bad9-eeb895c1f32f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_7ff40d16-c9e1-4c44-b79e-b783c0793c26" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_7ff40d16-c9e1-4c44-b79e-b783c0793c26" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_6fdd1565-b94e-49e3-8b37-f0859948f2a2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_8a3d815e-e6ed-4d13-8951-d67eaa8d2e9d" xlink:to="loc_us-gaap_StatementTable_6fdd1565-b94e-49e3-8b37-f0859948f2a2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_46d5b6e4-d272-4e86-baf6-8010c79f2bd7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_6fdd1565-b94e-49e3-8b37-f0859948f2a2" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_46d5b6e4-d272-4e86-baf6-8010c79f2bd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_46d5b6e4-d272-4e86-baf6-8010c79f2bd7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_46d5b6e4-d272-4e86-baf6-8010c79f2bd7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_46d5b6e4-d272-4e86-baf6-8010c79f2bd7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c0f4de4-6465-43df-b1b6-494bdf997551" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_46d5b6e4-d272-4e86-baf6-8010c79f2bd7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c0f4de4-6465-43df-b1b6-494bdf997551" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember_f8ba6ab4-0838-4fb7-bbd2-141347cf178e" xlink:href="sncy-20221231.xsd#sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6c0f4de4-6465-43df-b1b6-494bdf997551" xlink:to="loc_sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember_f8ba6ab4-0838-4fb7-bbd2-141347cf178e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_17eed4a5-093a-413e-8dcf-387ac7ee2a75" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_6fdd1565-b94e-49e3-8b37-f0859948f2a2" xlink:to="loc_us-gaap_TypeOfArrangementAxis_17eed4a5-093a-413e-8dcf-387ac7ee2a75" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_17eed4a5-093a-413e-8dcf-387ac7ee2a75_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_17eed4a5-093a-413e-8dcf-387ac7ee2a75" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_17eed4a5-093a-413e-8dcf-387ac7ee2a75_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_dc53b603-6bfb-468d-ae8b-072499a45e6b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_17eed4a5-093a-413e-8dcf-387ac7ee2a75" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_dc53b603-6bfb-468d-ae8b-072499a45e6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonAgreementMember_41f5b3b7-8320-445f-8bce-71080a37b652" xlink:href="sncy-20221231.xsd#sncy_AmazonAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_dc53b603-6bfb-468d-ae8b-072499a45e6b" xlink:to="loc_sncy_AmazonAgreementMember_41f5b3b7-8320-445f-8bce-71080a37b652" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_120b7467-2f82-48b1-8f28-9cf180f70f8d" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_6fdd1565-b94e-49e3-8b37-f0859948f2a2" xlink:to="loc_dei_LegalEntityAxis_120b7467-2f82-48b1-8f28-9cf180f70f8d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_120b7467-2f82-48b1-8f28-9cf180f70f8d_default" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_120b7467-2f82-48b1-8f28-9cf180f70f8d" xlink:to="loc_dei_EntityDomain_120b7467-2f82-48b1-8f28-9cf180f70f8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_85f6842c-5ec0-41d2-952a-77e2b4280f18" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_120b7467-2f82-48b1-8f28-9cf180f70f8d" xlink:to="loc_dei_EntityDomain_85f6842c-5ec0-41d2-952a-77e2b4280f18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember_67eebb51-aea8-4e8d-b234-a3b72631ab37" xlink:href="sncy-20221231.xsd#sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_85f6842c-5ec0-41d2-952a-77e2b4280f18" xlink:to="loc_sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember_67eebb51-aea8-4e8d-b234-a3b72631ab37" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/COMPANYBACKGROUNDEquityTransactionsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#COMPANYBACKGROUNDEquityTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/COMPANYBACKGROUNDEquityTransactionsDetails" xlink:type="extended" id="i4565d89f8f9048cc949d753bee195980_COMPANYBACKGROUNDEquityTransactionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_e73dca28-498f-4d7f-b708-e9283e074f5b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_e73dca28-498f-4d7f-b708-e9283e074f5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_81e31cbb-ac05-4c44-ae4d-bc9e06c77c06" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_81e31cbb-ac05-4c44-ae4d-bc9e06c77c06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_ee2748d3-5670-4274-860d-80614b887c10" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_ee2748d3-5670-4274-860d-80614b887c10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_6501f3f8-4780-4c2e-be40-4aea0ed0fbc3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_6501f3f8-4780-4c2e-be40-4aea0ed0fbc3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_c1a1a7e3-fd92-41de-99f8-b33baa0cced6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_c1a1a7e3-fd92-41de-99f8-b33baa0cced6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsExercised_a005aa2e-77de-4217-9b83-1b269f6486c6" xlink:href="sncy-20221231.xsd#sncy_WarrantsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_sncy_WarrantsExercised_a005aa2e-77de-4217-9b83-1b269f6486c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesIssued1_bcae8609-f536-458f-aac1-1e7779ba40d4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NotesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_us-gaap_NotesIssued1_bcae8609-f536-458f-aac1-1e7779ba40d4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfStockholders_fdf59445-a018-4bdb-8c71-cdb11c298748" xlink:href="sncy-20221231.xsd#sncy_NumberOfStockholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_sncy_NumberOfStockholders_fdf59445-a018-4bdb-8c71-cdb11c298748" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_c064fed1-25b7-44ec-8f2e-2f1c759378cd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_f42d35bf-c2f5-4a77-b680-18592c9a1c8c" xlink:to="loc_us-gaap_StatementTable_c064fed1-25b7-44ec-8f2e-2f1c759378cd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_af9e3255-8028-4abf-9f5c-846207633bd5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c064fed1-25b7-44ec-8f2e-2f1c759378cd" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_af9e3255-8028-4abf-9f5c-846207633bd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_af9e3255-8028-4abf-9f5c-846207633bd5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_af9e3255-8028-4abf-9f5c-846207633bd5" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_af9e3255-8028-4abf-9f5c-846207633bd5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b85fa0fd-156e-4814-a457-b014830d5688" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_af9e3255-8028-4abf-9f5c-846207633bd5" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b85fa0fd-156e-4814-a457-b014830d5688" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember_1c19a1aa-f306-4d2f-9243-c90f76b0d04b" xlink:href="sncy-20221231.xsd#sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b85fa0fd-156e-4814-a457-b014830d5688" xlink:to="loc_sncy_ApolloGlobalManagementInc.AndItsSubsidiariesMember_1c19a1aa-f306-4d2f-9243-c90f76b0d04b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_93d64a9b-c165-4d27-a79b-eb36d0550ad8" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c064fed1-25b7-44ec-8f2e-2f1c759378cd" xlink:to="loc_srt_OwnershipAxis_93d64a9b-c165-4d27-a79b-eb36d0550ad8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_93d64a9b-c165-4d27-a79b-eb36d0550ad8_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_93d64a9b-c165-4d27-a79b-eb36d0550ad8" xlink:to="loc_srt_OwnershipDomain_93d64a9b-c165-4d27-a79b-eb36d0550ad8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_ed3fea0a-e9be-470f-943a-ce81f6192a06" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_93d64a9b-c165-4d27-a79b-eb36d0550ad8" xlink:to="loc_srt_OwnershipDomain_ed3fea0a-e9be-470f-943a-ce81f6192a06" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/COMPANYBACKGROUNDInitialPublicOfferingDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#COMPANYBACKGROUNDInitialPublicOfferingDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/COMPANYBACKGROUNDInitialPublicOfferingDetails" xlink:type="extended" id="i9c5ba2484d954101aa9136a09cd79329_COMPANYBACKGROUNDInitialPublicOfferingDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_83f87fa5-1930-4b9f-a597-99522f2c3e04" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_83f87fa5-1930-4b9f-a597-99522f2c3e04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssuedPricePerShare_a2bf58f3-1c24-4b30-8c39-997a9add7f67" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharesIssuedPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_SharesIssuedPricePerShare_a2bf58f3-1c24-4b30-8c39-997a9add7f67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_4b0fd128-d705-4b8d-b8be-5c56cfe95a76" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_4b0fd128-d705-4b8d-b8be-5c56cfe95a76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AggregatePurchasePriceOfSharesIssued_9c6c3486-a6d3-40a1-bfab-99fa423ad38a" xlink:href="sncy-20221231.xsd#sncy_AggregatePurchasePriceOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_AggregatePurchasePriceOfSharesIssued_9c6c3486-a6d3-40a1-bfab-99fa423ad38a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_SharePriceAsPercentageOfIPOSharePrice_7476825b-6652-42a6-9a7d-4f782d99ebcb" xlink:href="sncy-20221231.xsd#sncy_SharePriceAsPercentageOfIPOSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_SharePriceAsPercentageOfIPOSharePrice_7476825b-6652-42a6-9a7d-4f782d99ebcb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_8d6a495a-4f84-4477-8647-321a28521c56" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_8d6a495a-4f84-4477-8647-321a28521c56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_6e421743-c4a2-4373-9db9-db5f83aeeee6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_6e421743-c4a2-4373-9db9-db5f83aeeee6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TermOfAgreement_1753f13b-ce38-4751-b080-50800b93fe80" xlink:href="sncy-20221231.xsd#sncy_TermOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_TermOfAgreement_1753f13b-ce38-4751-b080-50800b93fe80" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfExtensionOptions_70805e61-48f7-4616-b834-8d02cfe083b2" xlink:href="sncy-20221231.xsd#sncy_NumberOfExtensionOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_NumberOfExtensionOptions_70805e61-48f7-4616-b834-8d02cfe083b2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TermOfRenewalOfAgreement_8e740514-054d-413c-a5fc-fc03b75061c0" xlink:href="sncy-20221231.xsd#sncy_TermOfRenewalOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_TermOfRenewalOfAgreement_8e740514-054d-413c-a5fc-fc03b75061c0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ThresholdTermOfAgreement_27217d9a-7c97-4ba1-a74a-a273d8683a45" xlink:href="sncy-20221231.xsd#sncy_ThresholdTermOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_ThresholdTermOfAgreement_27217d9a-7c97-4ba1-a74a-a273d8683a45" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_6f2aa57b-1307-4ce4-92cf-05306240136a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_6f2aa57b-1307-4ce4-92cf-05306240136a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_6b564115-66da-4827-86d3-b5004e2b362a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_6b564115-66da-4827-86d3-b5004e2b362a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsVestedDuringPeriod_04727da5-d597-4b24-a860-6ec54762fad7" xlink:href="sncy-20221231.xsd#sncy_WarrantsVestedDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_WarrantsVestedDuringPeriod_04727da5-d597-4b24-a860-6ec54762fad7" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfWarrantsThatVestOnAchievementOfEachMilestone_decf04f7-02fd-4a0d-b351-405abfecfff1" xlink:href="sncy-20221231.xsd#sncy_NumberOfWarrantsThatVestOnAchievementOfEachMilestone"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_NumberOfWarrantsThatVestOnAchievementOfEachMilestone_decf04f7-02fd-4a0d-b351-405abfecfff1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantVestingConditionMilestoneAchievementQualifyingPaymentsReceivable_a77ed036-96fa-439f-bb70-b7627819998f" xlink:href="sncy-20221231.xsd#sncy_WarrantVestingConditionMilestoneAchievementQualifyingPaymentsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_WarrantVestingConditionMilestoneAchievementQualifyingPaymentsReceivable_a77ed036-96fa-439f-bb70-b7627819998f" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsVestedDuringPeriodHeld_46648135-4a1b-44cd-b928-de916468683b" xlink:href="sncy-20221231.xsd#sncy_WarrantsVestedDuringPeriodHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_sncy_WarrantsVestedDuringPeriodHeld_46648135-4a1b-44cd-b928-de916468683b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_7211be92-1757-4fee-a560-578259a789cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_acef90c4-0470-4f4b-b0a8-eb99cd6eafb4" xlink:to="loc_us-gaap_StatementTable_7211be92-1757-4fee-a560-578259a789cf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_83106384-594c-41cc-9bdd-4250f138c114" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7211be92-1757-4fee-a560-578259a789cf" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_83106384-594c-41cc-9bdd-4250f138c114" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_83106384-594c-41cc-9bdd-4250f138c114_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_83106384-594c-41cc-9bdd-4250f138c114" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_83106384-594c-41cc-9bdd-4250f138c114_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50ffa99f-c735-4fcb-87cf-d6c9d8065b28" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_83106384-594c-41cc-9bdd-4250f138c114" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50ffa99f-c735-4fcb-87cf-d6c9d8065b28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_44393bd2-fa79-4218-916c-7741ab9f4494" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50ffa99f-c735-4fcb-87cf-d6c9d8065b28" xlink:to="loc_us-gaap_IPOMember_44393bd2-fa79-4218-916c-7741ab9f4494" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OverAllotmentOptionMember_57541933-fba1-4d84-940c-a373688fc1db" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OverAllotmentOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50ffa99f-c735-4fcb-87cf-d6c9d8065b28" xlink:to="loc_us-gaap_OverAllotmentOptionMember_57541933-fba1-4d84-940c-a373688fc1db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember_476e0e40-e0b7-46ac-bd8f-b8a5c474cbc8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PrivatePlacementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50ffa99f-c735-4fcb-87cf-d6c9d8065b28" xlink:to="loc_us-gaap_PrivatePlacementMember_476e0e40-e0b7-46ac-bd8f-b8a5c474cbc8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_7c7dc7a0-86ff-4b8c-bcea-0b58953a5547" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7211be92-1757-4fee-a560-578259a789cf" xlink:to="loc_dei_LegalEntityAxis_7c7dc7a0-86ff-4b8c-bcea-0b58953a5547" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7c7dc7a0-86ff-4b8c-bcea-0b58953a5547_default" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_7c7dc7a0-86ff-4b8c-bcea-0b58953a5547" xlink:to="loc_dei_EntityDomain_7c7dc7a0-86ff-4b8c-bcea-0b58953a5547_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_5f868838-1ca3-4bdd-887e-467970ca44c2" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_7c7dc7a0-86ff-4b8c-bcea-0b58953a5547" xlink:to="loc_dei_EntityDomain_5f868838-1ca3-4bdd-887e-467970ca44c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ScaHorusHoldingsLlcMember_ba2b1b20-3c0e-4230-9734-85e05683c97e" xlink:href="sncy-20221231.xsd#sncy_ScaHorusHoldingsLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_5f868838-1ca3-4bdd-887e-467970ca44c2" xlink:to="loc_sncy_ScaHorusHoldingsLlcMember_ba2b1b20-3c0e-4230-9734-85e05683c97e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_90d52569-40f6-44c8-95c1-2dd578544282" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7211be92-1757-4fee-a560-578259a789cf" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_90d52569-40f6-44c8-95c1-2dd578544282" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_90d52569-40f6-44c8-95c1-2dd578544282_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_90d52569-40f6-44c8-95c1-2dd578544282" xlink:to="loc_us-gaap_RelatedPartyDomain_90d52569-40f6-44c8-95c1-2dd578544282_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_eda645a6-d73e-4b4e-90f8-e0f432105f84" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_90d52569-40f6-44c8-95c1-2dd578544282" xlink:to="loc_us-gaap_RelatedPartyDomain_eda645a6-d73e-4b4e-90f8-e0f432105f84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ChiefExecutiveOfficerMember_497670c0-6e8d-4608-a976-c549e782bf28" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ChiefExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_eda645a6-d73e-4b4e-90f8-e0f432105f84" xlink:to="loc_srt_ChiefExecutiveOfficerMember_497670c0-6e8d-4608-a976-c549e782bf28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_e0bf1a77-5994-4c3e-a31d-526711f67ca1" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7211be92-1757-4fee-a560-578259a789cf" xlink:to="loc_srt_CounterpartyNameAxis_e0bf1a77-5994-4c3e-a31d-526711f67ca1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_e0bf1a77-5994-4c3e-a31d-526711f67ca1_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_e0bf1a77-5994-4c3e-a31d-526711f67ca1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_e0bf1a77-5994-4c3e-a31d-526711f67ca1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_0f9e18b0-ad30-4966-8287-d9cb6f7967a9" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_e0bf1a77-5994-4c3e-a31d-526711f67ca1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_0f9e18b0-ad30-4966-8287-d9cb6f7967a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PRInvestmentPartnersL.pMember_33c54098-dc16-4707-a37b-e0597d32856f" xlink:href="sncy-20221231.xsd#sncy_PRInvestmentPartnersL.pMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_0f9e18b0-ad30-4966-8287-d9cb6f7967a9" xlink:to="loc_sncy_PRInvestmentPartnersL.pMember_33c54098-dc16-4707-a37b-e0597d32856f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CertainFundsOrAccountsManagedByInvestmentAdviserSubsidiaryOfBlackrockIncMember_4ba7e90f-6e6e-42da-810d-72b1d537e7a3" xlink:href="sncy-20221231.xsd#sncy_CertainFundsOrAccountsManagedByInvestmentAdviserSubsidiaryOfBlackrockIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_0f9e18b0-ad30-4966-8287-d9cb6f7967a9" xlink:to="loc_sncy_CertainFundsOrAccountsManagedByInvestmentAdviserSubsidiaryOfBlackrockIncMember_4ba7e90f-6e6e-42da-810d-72b1d537e7a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_ca3f0596-0875-4327-b700-3fdd65b77718" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7211be92-1757-4fee-a560-578259a789cf" xlink:to="loc_us-gaap_TypeOfArrangementAxis_ca3f0596-0875-4327-b700-3fdd65b77718" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_ca3f0596-0875-4327-b700-3fdd65b77718_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_ca3f0596-0875-4327-b700-3fdd65b77718" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_ca3f0596-0875-4327-b700-3fdd65b77718_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_c10a2f66-13e8-4f1b-b8c4-0a79753db91d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_ca3f0596-0875-4327-b700-3fdd65b77718" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_c10a2f66-13e8-4f1b-b8c4-0a79753db91d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonAgreementMember_b8fd2caa-ce31-47b8-b171-76bdd1a6f796" xlink:href="sncy-20221231.xsd#sncy_AmazonAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_c10a2f66-13e8-4f1b-b8c4-0a79753db91d" xlink:to="loc_sncy_AmazonAgreementMember_b8fd2caa-ce31-47b8-b171-76bdd1a6f796" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevenueRecognitionDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevenueRecognitionDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevenueRecognitionDetails" xlink:type="extended" id="i20b899eca9124e469302fffbc71de3dd_BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevenueRecognitionDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TravelCreditsTerm_bb3771b4-2c95-4bcf-a665-a68f7f3555a3" xlink:href="sncy-20221231.xsd#sncy_TravelCreditsTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_sncy_TravelCreditsTerm_bb3771b4-2c95-4bcf-a665-a68f7f3555a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TermOfAgreement_6ab9879a-d378-4a89-b407-7d64d739e958" xlink:href="sncy-20221231.xsd#sncy_TermOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_sncy_TermOfAgreement_6ab9879a-d378-4a89-b407-7d64d739e958" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfExtensionOptions_fa64c99e-98e9-4089-94b3-2045a3d4554e" xlink:href="sncy-20221231.xsd#sncy_NumberOfExtensionOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_sncy_NumberOfExtensionOptions_fa64c99e-98e9-4089-94b3-2045a3d4554e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TermOfRenewalOfAgreement_fab15508-692e-4bbc-a583-8f4da7f94922" xlink:href="sncy-20221231.xsd#sncy_TermOfRenewalOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_sncy_TermOfRenewalOfAgreement_fab15508-692e-4bbc-a583-8f4da7f94922" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ThresholdTermOfAgreement_0ea70320-bd3f-4987-ba91-92321649aa57" xlink:href="sncy-20221231.xsd#sncy_ThresholdTermOfAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_sncy_ThresholdTermOfAgreement_0ea70320-bd3f-4987-ba91-92321649aa57" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ContractWithCustomerNoticeOfExpiration_ad5414d7-0a41-4db0-9111-8c7da971e9c6" xlink:href="sncy-20221231.xsd#sncy_ContractWithCustomerNoticeOfExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_sncy_ContractWithCustomerNoticeOfExpiration_ad5414d7-0a41-4db0-9111-8c7da971e9c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ContractWithCustomerNumberOfPerformanceObligations_b8c5124d-c2d6-47e2-8714-8f25fff27daf" xlink:href="sncy-20221231.xsd#sncy_ContractWithCustomerNumberOfPerformanceObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_sncy_ContractWithCustomerNumberOfPerformanceObligations_b8c5124d-c2d6-47e2-8714-8f25fff27daf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_f99d70cb-75e7-4866-84aa-5953949e2aff" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4d882081-7ba4-4e35-a246-838854fdef51" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_f99d70cb-75e7-4866-84aa-5953949e2aff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_6fb7e8e0-2334-4150-8311-e03fb696b264" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_f99d70cb-75e7-4866-84aa-5953949e2aff" xlink:to="loc_us-gaap_TypeOfArrangementAxis_6fb7e8e0-2334-4150-8311-e03fb696b264" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_6fb7e8e0-2334-4150-8311-e03fb696b264_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_6fb7e8e0-2334-4150-8311-e03fb696b264" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_6fb7e8e0-2334-4150-8311-e03fb696b264_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_f15e2ca7-fd4f-47ff-a134-51f4a8afb9a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_6fb7e8e0-2334-4150-8311-e03fb696b264" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_f15e2ca7-fd4f-47ff-a134-51f4a8afb9a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonAgreementMember_f701e3e9-2910-460c-bd71-a2de25e86c23" xlink:href="sncy-20221231.xsd#sncy_AmazonAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_f15e2ca7-fd4f-47ff-a134-51f4a8afb9a3" xlink:to="loc_sncy_AmazonAgreementMember_f701e3e9-2910-460c-bd71-a2de25e86c23" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAccountsReceivableDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAccountsReceivableDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAccountsReceivableDetails" xlink:type="extended" id="i0b381cd87c544c49aa8537bd5bd70217_BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAccountsReceivableDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_aaa16be6-5761-4f3d-9fb3-6634b0141e6f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_5a7a9238-6e08-46a2-9c82-1b7367613675" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_aaa16be6-5761-4f3d-9fb3-6634b0141e6f" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_5a7a9238-6e08-46a2-9c82-1b7367613675" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_1bc8a995-bd2e-4714-9e81-953710c24c1d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_aaa16be6-5761-4f3d-9fb3-6634b0141e6f" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_1bc8a995-bd2e-4714-9e81-953710c24c1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a4992e1-3842-475a-9318-3ca56f89a07d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_aaa16be6-5761-4f3d-9fb3-6634b0141e6f" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a4992e1-3842-475a-9318-3ca56f89a07d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_25ffa5f2-aaf1-4a00-b918-41ed89054666" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a4992e1-3842-475a-9318-3ca56f89a07d" xlink:to="loc_srt_MajorCustomersAxis_25ffa5f2-aaf1-4a00-b918-41ed89054666" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_25ffa5f2-aaf1-4a00-b918-41ed89054666_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_25ffa5f2-aaf1-4a00-b918-41ed89054666" xlink:to="loc_srt_NameOfMajorCustomerDomain_25ffa5f2-aaf1-4a00-b918-41ed89054666_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_63f823da-c610-4ebd-874f-e68ec33d2df5" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_25ffa5f2-aaf1-4a00-b918-41ed89054666" xlink:to="loc_srt_NameOfMajorCustomerDomain_63f823da-c610-4ebd-874f-e68ec33d2df5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonMember_246c541f-3976-4aa8-8dbd-79abbc9e618a" xlink:href="sncy-20221231.xsd#sncy_AmazonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_63f823da-c610-4ebd-874f-e68ec33d2df5" xlink:to="loc_sncy_AmazonMember_246c541f-3976-4aa8-8dbd-79abbc9e618a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESInventoryDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESInventoryDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESInventoryDetails" xlink:type="extended" id="i57299135d80041fbaa9b9de9813cb1e4_BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESInventoryDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45ad9705-f345-4e9f-83a0-8c738d5c59e2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_InventoryResidualValuePercent_5d20dd15-eadf-4e00-89ad-717858399a3d" xlink:href="sncy-20221231.xsd#sncy_InventoryResidualValuePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45ad9705-f345-4e9f-83a0-8c738d5c59e2" xlink:to="loc_sncy_InventoryResidualValuePercent_5d20dd15-eadf-4e00-89ad-717858399a3d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_9a7ef02e-8e41-41d6-922e-2b48d76724e3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45ad9705-f345-4e9f-83a0-8c738d5c59e2" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_9a7ef02e-8e41-41d6-922e-2b48d76724e3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e16c0990-bba9-425c-acd5-4ab857271075" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_9a7ef02e-8e41-41d6-922e-2b48d76724e3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e16c0990-bba9-425c-acd5-4ab857271075" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e16c0990-bba9-425c-acd5-4ab857271075_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e16c0990-bba9-425c-acd5-4ab857271075" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e16c0990-bba9-425c-acd5-4ab857271075_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_af6263b4-71b4-4887-aa4e-dc04e7d5a001" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e16c0990-bba9-425c-acd5-4ab857271075" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_af6263b4-71b4-4887-aa4e-dc04e7d5a001" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PartsRelatedToFlightEquipmentMember_83e75a9f-093e-45ae-9a23-88715bdb74eb" xlink:href="sncy-20221231.xsd#sncy_PartsRelatedToFlightEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_af6263b4-71b4-4887-aa4e-dc04e7d5a001" xlink:to="loc_sncy_PartsRelatedToFlightEquipmentMember_83e75a9f-093e-45ae-9a23-88715bdb74eb" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPropertyandEquipmentDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPropertyandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPropertyandEquipmentDetails" xlink:type="extended" id="ic827e76e740a402b9c20746ff97776ea_BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPropertyandEquipmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_404848c8-b749-4218-868f-ba74f4759b50" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_b123a6c7-2376-4bfa-a834-9d76747a25c4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_404848c8-b749-4218-868f-ba74f4759b50" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_b123a6c7-2376-4bfa-a834-9d76747a25c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_5fc27009-2bf9-4a44-aaed-f01a846d2a8e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_404848c8-b749-4218-868f-ba74f4759b50" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_5fc27009-2bf9-4a44-aaed-f01a846d2a8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_4106f71e-01eb-446b-aeac-4377b2978189" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_404848c8-b749-4218-868f-ba74f4759b50" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_4106f71e-01eb-446b-aeac-4377b2978189" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4f991ca1-aa2d-4008-a754-8db7733c1830" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_4106f71e-01eb-446b-aeac-4377b2978189" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4f991ca1-aa2d-4008-a754-8db7733c1830" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4f991ca1-aa2d-4008-a754-8db7733c1830_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4f991ca1-aa2d-4008-a754-8db7733c1830" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4f991ca1-aa2d-4008-a754-8db7733c1830_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4f991ca1-aa2d-4008-a754-8db7733c1830" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AirTransportationEquipmentAirframesMember_1e6f191c-1f56-4d37-bb63-dfd1b2af4c2a" xlink:href="sncy-20221231.xsd#sncy_AirTransportationEquipmentAirframesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:to="loc_sncy_AirTransportationEquipmentAirframesMember_1e6f191c-1f56-4d37-bb63-dfd1b2af4c2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AirTransportationEquipmentCoreEnginesMember_318c41fc-3794-4e47-aa0e-ddcb00fa0ef5" xlink:href="sncy-20221231.xsd#sncy_AirTransportationEquipmentCoreEnginesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:to="loc_sncy_AirTransportationEquipmentCoreEnginesMember_318c41fc-3794-4e47-aa0e-ddcb00fa0ef5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_fdc0f3e2-de96-4023-b469-c292ce396351" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_fdc0f3e2-de96-4023-b469-c292ce396351" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember_fd47157a-c267-4c11-bd52-fb7ca37e25d4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:to="loc_us-gaap_EquipmentMember_fd47157a-c267-4c11-bd52-fb7ca37e25d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_34ba4733-97ca-4435-a32d-39d655fc6680" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:to="loc_us-gaap_ComputerEquipmentMember_34ba4733-97ca-4435-a32d-39d655fc6680" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_RotablePartsMember_a73666bb-074a-41d9-825e-c7a9e2200864" xlink:href="sncy-20221231.xsd#sncy_RotablePartsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_40d2eaa2-eea1-489f-9bf2-2703fef28a58" xlink:to="loc_sncy_RotablePartsMember_a73666bb-074a-41d9-825e-c7a9e2200864" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_1f622e26-7687-44c9-ba09-429ad50077f5" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_4106f71e-01eb-446b-aeac-4377b2978189" xlink:to="loc_srt_RangeAxis_1f622e26-7687-44c9-ba09-429ad50077f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1f622e26-7687-44c9-ba09-429ad50077f5_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_1f622e26-7687-44c9-ba09-429ad50077f5" xlink:to="loc_srt_RangeMember_1f622e26-7687-44c9-ba09-429ad50077f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b645e8b0-6b28-4690-80ef-6db82bfce7d3" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_1f622e26-7687-44c9-ba09-429ad50077f5" xlink:to="loc_srt_RangeMember_b645e8b0-6b28-4690-80ef-6db82bfce7d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_cb56ad4d-ff1c-419e-a46d-1a66d3f98c62" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b645e8b0-6b28-4690-80ef-6db82bfce7d3" xlink:to="loc_srt_MinimumMember_cb56ad4d-ff1c-419e-a46d-1a66d3f98c62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_9e5ff179-eb14-4cf8-aeb9-eef3ec4fd644" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b645e8b0-6b28-4690-80ef-6db82bfce7d3" xlink:to="loc_srt_MaximumMember_9e5ff179-eb14-4cf8-aeb9-eef3ec4fd644" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESConcentrationRiskDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESConcentrationRiskDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESConcentrationRiskDetails" xlink:type="extended" id="i86eafcd2864b4ca9bad041793260e5f7_BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESConcentrationRiskDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_e9f24437-7598-407a-bef5-8c4af1a4899f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_87f9e59f-7836-4100-b5a5-70c38f9ec135" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_e9f24437-7598-407a-bef5-8c4af1a4899f" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_87f9e59f-7836-4100-b5a5-70c38f9ec135" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfVendors_7d071f39-4692-4c64-8234-a01e1b422904" xlink:href="sncy-20221231.xsd#sncy_NumberOfVendors"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_e9f24437-7598-407a-bef5-8c4af1a4899f" xlink:to="loc_sncy_NumberOfVendors_7d071f39-4692-4c64-8234-a01e1b422904" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfUnions_6b73656f-c81b-41c1-919b-7a723f4ab0ec" xlink:href="sncy-20221231.xsd#sncy_NumberOfUnions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_e9f24437-7598-407a-bef5-8c4af1a4899f" xlink:to="loc_sncy_NumberOfUnions_6b73656f-c81b-41c1-919b-7a723f4ab0ec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityNumberOfEmployees_bdeefce5-a281-401d-9c16-2c8a6feb85e4" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityNumberOfEmployees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_e9f24437-7598-407a-bef5-8c4af1a4899f" xlink:to="loc_dei_EntityNumberOfEmployees_bdeefce5-a281-401d-9c16-2c8a6feb85e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_e9f24437-7598-407a-bef5-8c4af1a4899f" xlink:to="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_83e565fd-83d6-4b59-a9f5-0ccf7cc1ef61" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_83e565fd-83d6-4b59-a9f5-0ccf7cc1ef61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_83e565fd-83d6-4b59-a9f5-0ccf7cc1ef61_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_83e565fd-83d6-4b59-a9f5-0ccf7cc1ef61" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_83e565fd-83d6-4b59-a9f5-0ccf7cc1ef61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01084753-86c2-4809-bb66-c80bef4879c7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_83e565fd-83d6-4b59-a9f5-0ccf7cc1ef61" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01084753-86c2-4809-bb66-c80bef4879c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_4372e895-d006-43eb-a6c0-1761ee6d8163" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01084753-86c2-4809-bb66-c80bef4879c7" xlink:to="loc_us-gaap_AccountsReceivableMember_4372e895-d006-43eb-a6c0-1761ee6d8163" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsTotalMember_924d124f-79cb-44f6-9e36-154983250c66" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CostOfGoodsTotalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01084753-86c2-4809-bb66-c80bef4879c7" xlink:to="loc_us-gaap_CostOfGoodsTotalMember_924d124f-79cb-44f6-9e36-154983250c66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WorkforceSubjectToCollectiveBargainingArrangementsMember_00b6ef80-4395-4d0a-b888-5b9ef2199a75" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WorkforceSubjectToCollectiveBargainingArrangementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01084753-86c2-4809-bb66-c80bef4879c7" xlink:to="loc_us-gaap_WorkforceSubjectToCollectiveBargainingArrangementsMember_00b6ef80-4395-4d0a-b888-5b9ef2199a75" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WorkforceSubjectToCollectiveBargainingArrangementsExpiringWithinOneYearMember_514601b2-382e-437e-86b9-058526f9a53d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WorkforceSubjectToCollectiveBargainingArrangementsExpiringWithinOneYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01084753-86c2-4809-bb66-c80bef4879c7" xlink:to="loc_us-gaap_WorkforceSubjectToCollectiveBargainingArrangementsExpiringWithinOneYearMember_514601b2-382e-437e-86b9-058526f9a53d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_567c8b49-de5d-4849-90d4-b5c95e17e610" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_567c8b49-de5d-4849-90d4-b5c95e17e610" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_567c8b49-de5d-4849-90d4-b5c95e17e610_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_567c8b49-de5d-4849-90d4-b5c95e17e610" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_567c8b49-de5d-4849-90d4-b5c95e17e610_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_92a69aea-2605-40ba-a004-eb4444a7876e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_567c8b49-de5d-4849-90d4-b5c95e17e610" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_92a69aea-2605-40ba-a004-eb4444a7876e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_04784265-cbce-42e2-9048-97df79af6886" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_92a69aea-2605-40ba-a004-eb4444a7876e" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_04784265-cbce-42e2-9048-97df79af6886" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierConcentrationRiskMember_78dd2b4a-54fe-4023-a8fb-ca98935cc580" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SupplierConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_92a69aea-2605-40ba-a004-eb4444a7876e" xlink:to="loc_us-gaap_SupplierConcentrationRiskMember_78dd2b4a-54fe-4023-a8fb-ca98935cc580" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnionizedEmployeesConcentrationRiskMember_0b20871a-412d-4ffc-9abd-3ae704f57bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnionizedEmployeesConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_92a69aea-2605-40ba-a004-eb4444a7876e" xlink:to="loc_us-gaap_UnionizedEmployeesConcentrationRiskMember_0b20871a-412d-4ffc-9abd-3ae704f57bf5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_009b8b27-3e6a-4308-92bb-3c1c7062807a" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:to="loc_srt_MajorCustomersAxis_009b8b27-3e6a-4308-92bb-3c1c7062807a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_009b8b27-3e6a-4308-92bb-3c1c7062807a_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_009b8b27-3e6a-4308-92bb-3c1c7062807a" xlink:to="loc_srt_NameOfMajorCustomerDomain_009b8b27-3e6a-4308-92bb-3c1c7062807a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_249e0d46-e5e6-40c4-993e-ba1ad5caa86a" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_009b8b27-3e6a-4308-92bb-3c1c7062807a" xlink:to="loc_srt_NameOfMajorCustomerDomain_249e0d46-e5e6-40c4-993e-ba1ad5caa86a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonMember_2515167e-4c57-4623-901b-bd914eb1a0de" xlink:href="sncy-20221231.xsd#sncy_AmazonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_249e0d46-e5e6-40c4-993e-ba1ad5caa86a" xlink:to="loc_sncy_AmazonMember_2515167e-4c57-4623-901b-bd914eb1a0de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CustomerMember_3d936fde-76eb-4ed9-98fb-009c66389365" xlink:href="sncy-20221231.xsd#sncy_CustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_249e0d46-e5e6-40c4-993e-ba1ad5caa86a" xlink:to="loc_sncy_CustomerMember_3d936fde-76eb-4ed9-98fb-009c66389365" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TwoVendorsMember_8c9f6b00-5d55-4fbe-95da-9efce1faf0bc" xlink:href="sncy-20221231.xsd#sncy_TwoVendorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_249e0d46-e5e6-40c4-993e-ba1ad5caa86a" xlink:to="loc_sncy_TwoVendorsMember_8c9f6b00-5d55-4fbe-95da-9efce1faf0bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollectiveBargainingArrangementAxis_f47fe85d-fe9f-4d39-8c51-5575dd419dc8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CollectiveBargainingArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:to="loc_us-gaap_CollectiveBargainingArrangementAxis_f47fe85d-fe9f-4d39-8c51-5575dd419dc8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollectiveBargainingArrangementDomain_f47fe85d-fe9f-4d39-8c51-5575dd419dc8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CollectiveBargainingArrangementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CollectiveBargainingArrangementAxis_f47fe85d-fe9f-4d39-8c51-5575dd419dc8" xlink:to="loc_us-gaap_CollectiveBargainingArrangementDomain_f47fe85d-fe9f-4d39-8c51-5575dd419dc8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollectiveBargainingArrangementDomain_73bd584c-b111-4331-9489-3611afd50139" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CollectiveBargainingArrangementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CollectiveBargainingArrangementAxis_f47fe85d-fe9f-4d39-8c51-5575dd419dc8" xlink:to="loc_us-gaap_CollectiveBargainingArrangementDomain_73bd584c-b111-4331-9489-3611afd50139" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AirLinePilotsAssociationMember_1f83047e-4f8b-423a-b7dd-b2c9b4999aa0" xlink:href="sncy-20221231.xsd#sncy_AirLinePilotsAssociationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollectiveBargainingArrangementDomain_73bd584c-b111-4331-9489-3611afd50139" xlink:to="loc_sncy_AirLinePilotsAssociationMember_1f83047e-4f8b-423a-b7dd-b2c9b4999aa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_InternationalBrotherhoodOfTeamstersMember_0577f60a-6101-4222-ae9b-2ef99d2eb1dd" xlink:href="sncy-20221231.xsd#sncy_InternationalBrotherhoodOfTeamstersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollectiveBargainingArrangementDomain_73bd584c-b111-4331-9489-3611afd50139" xlink:to="loc_sncy_InternationalBrotherhoodOfTeamstersMember_0577f60a-6101-4222-ae9b-2ef99d2eb1dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TransportWorkersUnionMember_b0a05643-f060-433e-bfd2-bd712d45a461" xlink:href="sncy-20221231.xsd#sncy_TransportWorkersUnionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollectiveBargainingArrangementDomain_73bd584c-b111-4331-9489-3611afd50139" xlink:to="loc_sncy_TransportWorkersUnionMember_b0a05643-f060-433e-bfd2-bd712d45a461" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AMFAMember_471b7b67-7004-41a9-8b62-f272805b5b23" xlink:href="sncy-20221231.xsd#sncy_AMFAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollectiveBargainingArrangementDomain_73bd584c-b111-4331-9489-3611afd50139" xlink:to="loc_sncy_AMFAMember_471b7b67-7004-41a9-8b62-f272805b5b23" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_29f4386f-c46d-4eae-aca4-a8fd4720570b" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:to="loc_srt_RangeAxis_29f4386f-c46d-4eae-aca4-a8fd4720570b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_29f4386f-c46d-4eae-aca4-a8fd4720570b_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_29f4386f-c46d-4eae-aca4-a8fd4720570b" xlink:to="loc_srt_RangeMember_29f4386f-c46d-4eae-aca4-a8fd4720570b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_8ab9f577-bb08-4945-8d89-54d802e8cd7c" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_29f4386f-c46d-4eae-aca4-a8fd4720570b" xlink:to="loc_srt_RangeMember_8ab9f577-bb08-4945-8d89-54d802e8cd7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b63f40f2-db7d-4264-87b9-fe02fdc3173b" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8ab9f577-bb08-4945-8d89-54d802e8cd7c" xlink:to="loc_srt_MaximumMember_b63f40f2-db7d-4264-87b9-fe02fdc3173b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_31f737b5-8bc3-4148-98a8-5f3e71095101" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_0e56b0a0-77ba-4d1b-b75c-0482ec1dd03d" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_31f737b5-8bc3-4148-98a8-5f3e71095101" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_31f737b5-8bc3-4148-98a8-5f3e71095101_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_31f737b5-8bc3-4148-98a8-5f3e71095101" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_31f737b5-8bc3-4148-98a8-5f3e71095101_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_482546e0-df2e-42d9-91c2-9c7c06f508f3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_31f737b5-8bc3-4148-98a8-5f3e71095101" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_482546e0-df2e-42d9-91c2-9c7c06f508f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_cb8cf690-20e2-43f6-bf14-c34459b1bdb2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_482546e0-df2e-42d9-91c2-9c7c06f508f3" xlink:to="loc_us-gaap_SubsequentEventMember_cb8cf690-20e2-43f6-bf14-c34459b1bdb2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevisionofPreviouslyIssuedConsolidatedFinancialStatementsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevisionofPreviouslyIssuedConsolidatedFinancialStatementsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevisionofPreviouslyIssuedConsolidatedFinancialStatementsDetails" xlink:type="extended" id="ie59470881c644e41bb5b6f7198ba760b_BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevisionofPreviouslyIssuedConsolidatedFinancialStatementsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9d52edaa-71d6-40c1-8a66-205053dec861" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BalanceSheetRelatedDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9d52edaa-71d6-40c1-8a66-205053dec861" xlink:to="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_cac52518-732d-481a-8db9-4ff049fcd348" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_cac52518-732d-481a-8db9-4ff049fcd348" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_a624334a-c898-43eb-92af-b6139e2da912" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_a624334a-c898-43eb-92af-b6139e2da912" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_24af4ea6-8c98-4f02-a965-bbd9387b8a1e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_24af4ea6-8c98-4f02-a965-bbd9387b8a1e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_a5c1ccec-c3cb-4322-bc8c-89cc4dbf8125" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_a5c1ccec-c3cb-4322-bc8c-89cc4dbf8125" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_7aafcdf0-4e4e-4620-a50c-82c883571c51" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_7aafcdf0-4e4e-4620-a50c-82c883571c51" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_4b1b59c7-3cd6-4395-a2fa-78503a74108c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_OtherAssets_4b1b59c7-3cd6-4395-a2fa-78503a74108c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_15bfdc2a-7fcb-4666-a21b-16e4669e386e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_Assets_15bfdc2a-7fcb-4666-a21b-16e4669e386e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_88c8e4d5-5273-4262-8b8f-e76f4048a744" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_88c8e4d5-5273-4262-8b8f-e76f4048a744" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_60d96a93-6a40-4a7b-b923-42ea856f4c40" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_StockholdersEquity_60d96a93-6a40-4a7b-b923-42ea856f4c40" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_f4dc8a0c-df06-4a6b-a04b-81118c98c7cb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetRelatedDisclosuresAbstract_de8a8593-b431-4a1b-a715-548af27b09f4" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_f4dc8a0c-df06-4a6b-a04b-81118c98c7cb" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9d52edaa-71d6-40c1-8a66-205053dec861" xlink:to="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_465b59dc-869d-448f-b5b1-c7634753a297" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_465b59dc-869d-448f-b5b1-c7634753a297" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemNetGainLoss_3cf23227-0328-4b36-82d1-92e9e2fdc3be" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemNetGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_UnusualOrInfrequentItemNetGainLoss_3cf23227-0328-4b36-82d1-92e9e2fdc3be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_b8018d68-b83e-4870-abf0-5c453ea02839" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_OperatingExpenses_b8018d68-b83e-4870-abf0-5c453ea02839" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_bd7c21d6-94a9-4d1e-9259-dfc016615927" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_OperatingIncomeLoss_bd7c21d6-94a9-4d1e-9259-dfc016615927" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_1d10e9ef-09a1-4fd8-96dc-6512dd288acf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_1d10e9ef-09a1-4fd8-96dc-6512dd288acf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_7d9e6ffd-918a-4705-b1ea-8c4acc4632ef" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_7d9e6ffd-918a-4705-b1ea-8c4acc4632ef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_60943815-5edf-4e64-bc7c-87b752ab0f39" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_NetIncomeLoss_60943815-5edf-4e64-bc7c-87b752ab0f39" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_d2099876-b290-4e58-9f15-c68bba0103a5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_EarningsPerShareBasic_d2099876-b290-4e58-9f15-c68bba0103a5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_001b0c45-3864-4de7-a229-9add15d35174" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_94563933-7f9f-43e4-9b43-d204b62ab2c5" xlink:to="loc_us-gaap_EarningsPerShareDiluted_001b0c45-3864-4de7-a229-9add15d35174" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_de238ad8-3a0b-4c86-ba12-a04ddd6c3770" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9d52edaa-71d6-40c1-8a66-205053dec861" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_de238ad8-3a0b-4c86-ba12-a04ddd6c3770" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_b2595f4d-cef4-4705-a4b4-6af1455a1344" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnDispositionOfAssets1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_de238ad8-3a0b-4c86-ba12-a04ddd6c3770" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_b2595f4d-cef4-4705-a4b4-6af1455a1344" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_d7cb9e4d-1f59-431c-b94f-5125b09bcd72" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_de238ad8-3a0b-4c86-ba12-a04ddd6c3770" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_d7cb9e4d-1f59-431c-b94f-5125b09bcd72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_ae523b8d-9c0f-4805-858c-a9cfbeecc210" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_de238ad8-3a0b-4c86-ba12-a04ddd6c3770" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_ae523b8d-9c0f-4805-858c-a9cfbeecc210" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_e5cc8c27-bcb1-4108-a79a-d22fb6a59721" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_de238ad8-3a0b-4c86-ba12-a04ddd6c3770" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_e5cc8c27-bcb1-4108-a79a-d22fb6a59721" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromInvestingActivitiesAbstract_5b21ec0f-8641-467d-ac92-9a35228ac1b1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9d52edaa-71d6-40c1-8a66-205053dec861" xlink:to="loc_us-gaap_ProceedsFromInvestingActivitiesAbstract_5b21ec0f-8641-467d-ac92-9a35228ac1b1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_214c0860-9ef4-48b4-ad17-4025f4bafcf3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromInvestingActivitiesAbstract_5b21ec0f-8641-467d-ac92-9a35228ac1b1" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_214c0860-9ef4-48b4-ad17-4025f4bafcf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_2514f957-c159-49eb-b475-89666159cb54" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromInvestingActivitiesAbstract_5b21ec0f-8641-467d-ac92-9a35228ac1b1" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_2514f957-c159-49eb-b475-89666159cb54" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_31e8fb9d-9619-44d0-bafc-3660b86b09c2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9d52edaa-71d6-40c1-8a66-205053dec861" xlink:to="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_31e8fb9d-9619-44d0-bafc-3660b86b09c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAxis_0b82fbfb-9e31-4cb1-a2f1-4856050850c7" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_31e8fb9d-9619-44d0-bafc-3660b86b09c2" xlink:to="loc_srt_RestatementAxis_0b82fbfb-9e31-4cb1-a2f1-4856050850c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_0b82fbfb-9e31-4cb1-a2f1-4856050850c7_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_0b82fbfb-9e31-4cb1-a2f1-4856050850c7" xlink:to="loc_srt_RestatementDomain_0b82fbfb-9e31-4cb1-a2f1-4856050850c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_cb543992-5b1b-40c6-8566-87f607a654c1" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_0b82fbfb-9e31-4cb1-a2f1-4856050850c7" xlink:to="loc_srt_RestatementDomain_cb543992-5b1b-40c6-8566-87f607a654c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioPreviouslyReportedMember_689002aa-7ec0-4a5a-bad3-40a868e91d4f" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScenarioPreviouslyReportedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_cb543992-5b1b-40c6-8566-87f607a654c1" xlink:to="loc_srt_ScenarioPreviouslyReportedMember_689002aa-7ec0-4a5a-bad3-40a868e91d4f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RevisionOfPriorPeriodErrorCorrectionAdjustmentMember_50764f84-4552-45cd-9d9d-a05e216ea857" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RevisionOfPriorPeriodErrorCorrectionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_cb543992-5b1b-40c6-8566-87f607a654c1" xlink:to="loc_srt_RevisionOfPriorPeriodErrorCorrectionAdjustmentMember_50764f84-4552-45cd-9d9d-a05e216ea857" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81a3e9c8-702e-49fc-937a-0569efb9d809" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_31e8fb9d-9619-44d0-bafc-3660b86b09c2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81a3e9c8-702e-49fc-937a-0569efb9d809" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_81a3e9c8-702e-49fc-937a-0569efb9d809_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81a3e9c8-702e-49fc-937a-0569efb9d809" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_81a3e9c8-702e-49fc-937a-0569efb9d809_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b0d170a6-fa0a-48c6-8744-991aaf7ffcd8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81a3e9c8-702e-49fc-937a-0569efb9d809" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b0d170a6-fa0a-48c6-8744-991aaf7ffcd8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AirTransportationEquipmentMember_a7b68079-9e18-4bf6-b6a2-05c90ad5f69b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AirTransportationEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b0d170a6-fa0a-48c6-8744-991aaf7ffcd8" xlink:to="loc_us-gaap_AirTransportationEquipmentMember_a7b68079-9e18-4bf6-b6a2-05c90ad5f69b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/IMPACTOFTHECOVID19PANDEMICDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#IMPACTOFTHECOVID19PANDEMICDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/IMPACTOFTHECOVID19PANDEMICDetails" xlink:type="extended" id="ibd5f4062bd4d4ab7a16410d318285305_IMPACTOFTHECOVID19PANDEMICDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemLineItems_2da08eb5-6aa2-470d-b56c-3a490a9e3b07" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CaresActGrantsRecognized_d7cefc68-fa3c-4c52-9940-5963c6851ba8" xlink:href="sncy-20221231.xsd#sncy_CaresActGrantsRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnusualOrInfrequentItemLineItems_2da08eb5-6aa2-470d-b56c-3a490a9e3b07" xlink:to="loc_sncy_CaresActGrantsRecognized_d7cefc68-fa3c-4c52-9940-5963c6851ba8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CaresActEmployeeRetentionCredit_e68a27ff-0a1e-4ea5-83df-6664f66c0df7" xlink:href="sncy-20221231.xsd#sncy_CaresActEmployeeRetentionCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnusualOrInfrequentItemLineItems_2da08eb5-6aa2-470d-b56c-3a490a9e3b07" xlink:to="loc_sncy_CaresActEmployeeRetentionCredit_e68a27ff-0a1e-4ea5-83df-6664f66c0df7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfDebt_39be0fcc-7a85-4d45-aa42-bcc4f6243fce" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnusualOrInfrequentItemLineItems_2da08eb5-6aa2-470d-b56c-3a490a9e3b07" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfDebt_39be0fcc-7a85-4d45-aa42-bcc4f6243fce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CompensationPayableLimitExceeded_42c76727-4dcc-493a-b7d3-3d7f7cc7e3c4" xlink:href="sncy-20221231.xsd#sncy_CompensationPayableLimitExceeded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnusualOrInfrequentItemLineItems_2da08eb5-6aa2-470d-b56c-3a490a9e3b07" xlink:to="loc_sncy_CompensationPayableLimitExceeded_42c76727-4dcc-493a-b7d3-3d7f7cc7e3c4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemTable_0d17b83a-824e-439c-9fe6-574d6d2992ad" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_UnusualOrInfrequentItemLineItems_2da08eb5-6aa2-470d-b56c-3a490a9e3b07" xlink:to="loc_us-gaap_UnusualOrInfrequentItemTable_0d17b83a-824e-439c-9fe6-574d6d2992ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemAxis_02b94a3d-c8b5-430f-abb2-af3589bf8519" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_UnusualOrInfrequentItemTable_0d17b83a-824e-439c-9fe6-574d6d2992ad" xlink:to="loc_us-gaap_UnusualOrInfrequentItemAxis_02b94a3d-c8b5-430f-abb2-af3589bf8519" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemDomain_02b94a3d-c8b5-430f-abb2-af3589bf8519_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_UnusualOrInfrequentItemAxis_02b94a3d-c8b5-430f-abb2-af3589bf8519" xlink:to="loc_us-gaap_UnusualOrInfrequentItemDomain_02b94a3d-c8b5-430f-abb2-af3589bf8519_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemDomain_e92a889c-258f-4518-a0c8-6447795220be" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_UnusualOrInfrequentItemAxis_02b94a3d-c8b5-430f-abb2-af3589bf8519" xlink:to="loc_us-gaap_UnusualOrInfrequentItemDomain_e92a889c-258f-4518-a0c8-6447795220be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CaresActGrantsUnderTreasuryUnderPayrollSupportProgramExtensionMember_c5535730-ccd9-4b1f-bf29-d528f1bef41e" xlink:href="sncy-20221231.xsd#sncy_CaresActGrantsUnderTreasuryUnderPayrollSupportProgramExtensionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnusualOrInfrequentItemDomain_e92a889c-258f-4518-a0c8-6447795220be" xlink:to="loc_sncy_CaresActGrantsUnderTreasuryUnderPayrollSupportProgramExtensionMember_c5535730-ccd9-4b1f-bf29-d528f1bef41e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_64a011dc-5c9e-43e6-a55c-fa623becef93" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_UnusualOrInfrequentItemTable_0d17b83a-824e-439c-9fe6-574d6d2992ad" xlink:to="loc_us-gaap_DebtInstrumentAxis_64a011dc-5c9e-43e6-a55c-fa623becef93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_64a011dc-5c9e-43e6-a55c-fa623becef93_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_64a011dc-5c9e-43e6-a55c-fa623becef93" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_64a011dc-5c9e-43e6-a55c-fa623becef93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_42282d89-e948-47ae-bca9-4c8a22faadfe" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_64a011dc-5c9e-43e6-a55c-fa623becef93" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_42282d89-e948-47ae-bca9-4c8a22faadfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CaresActLoanMember_cf5c6b82-0e75-497b-b240-269632af9459" xlink:href="sncy-20221231.xsd#sncy_CaresActLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_42282d89-e948-47ae-bca9-4c8a22faadfe" xlink:to="loc_sncy_CaresActLoanMember_cf5c6b82-0e75-497b-b240-269632af9459" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeAxis_626558d6-2cde-479d-b32a-ae856e981362" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GovernmentAssistanceTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_UnusualOrInfrequentItemTable_0d17b83a-824e-439c-9fe6-574d6d2992ad" xlink:to="loc_us-gaap_GovernmentAssistanceTypeAxis_626558d6-2cde-479d-b32a-ae856e981362" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_626558d6-2cde-479d-b32a-ae856e981362_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_626558d6-2cde-479d-b32a-ae856e981362" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_626558d6-2cde-479d-b32a-ae856e981362_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_8f7b8b9b-cad5-458b-aef7-36aaf666e10b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_626558d6-2cde-479d-b32a-ae856e981362" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_8f7b8b9b-cad5-458b-aef7-36aaf666e10b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CARESActMember_f0c937f5-e56f-4de3-9d86-831e6a7e66d5" xlink:href="sncy-20221231.xsd#sncy_CARESActMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GovernmentAssistanceTypeDomain_8f7b8b9b-cad5-458b-aef7-36aaf666e10b" xlink:to="loc_sncy_CARESActMember_f0c937f5-e56f-4de3-9d86-831e6a7e66d5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/REVENUEDisaggregationofOperatingRevenueDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#REVENUEDisaggregationofOperatingRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/REVENUEDisaggregationofOperatingRevenueDetails" xlink:type="extended" id="iedacac3dd7674484b5a599acf1de5e3a_REVENUEDisaggregationofOperatingRevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_474dfe03-dea9-49a7-8b81-b4ada45e0a0d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_f153ee64-0fd9-4256-8785-52d5e61cec00" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_474dfe03-dea9-49a7-8b81-b4ada45e0a0d" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_f153ee64-0fd9-4256-8785-52d5e61cec00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_ae9a8b0f-16e3-45b7-bca5-bf891bdab95b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_474dfe03-dea9-49a7-8b81-b4ada45e0a0d" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_ae9a8b0f-16e3-45b7-bca5-bf891bdab95b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_8ad9a9a1-79c7-4f6b-bb32-3caf6424d612" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_ae9a8b0f-16e3-45b7-bca5-bf891bdab95b" xlink:to="loc_srt_ProductOrServiceAxis_8ad9a9a1-79c7-4f6b-bb32-3caf6424d612" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_8ad9a9a1-79c7-4f6b-bb32-3caf6424d612_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_8ad9a9a1-79c7-4f6b-bb32-3caf6424d612" xlink:to="loc_srt_ProductsAndServicesDomain_8ad9a9a1-79c7-4f6b-bb32-3caf6424d612_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d64861af-5c34-4410-8201-edd0dfb94999" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_8ad9a9a1-79c7-4f6b-bb32-3caf6424d612" xlink:to="loc_srt_ProductsAndServicesDomain_d64861af-5c34-4410-8201-edd0dfb94999" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassengerMember_f94c408f-8076-43ff-b97e-7085bb3bdb5e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PassengerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d64861af-5c34-4410-8201-edd0dfb94999" xlink:to="loc_us-gaap_PassengerMember_f94c408f-8076-43ff-b97e-7085bb3bdb5e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ScheduledServiceMember_e20d83b7-fa29-4399-b0d7-799890c78161" xlink:href="sncy-20221231.xsd#sncy_ScheduledServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PassengerMember_f94c408f-8076-43ff-b97e-7085bb3bdb5e" xlink:to="loc_sncy_ScheduledServiceMember_e20d83b7-fa29-4399-b0d7-799890c78161" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CharterServiceMember_772332af-f3cc-46f7-b725-b62844f228f4" xlink:href="sncy-20221231.xsd#sncy_CharterServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PassengerMember_f94c408f-8076-43ff-b97e-7085bb3bdb5e" xlink:to="loc_sncy_CharterServiceMember_772332af-f3cc-46f7-b725-b62844f228f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AncillaryMember_b138ed8d-b507-46a9-b40d-3824ca038200" xlink:href="sncy-20221231.xsd#sncy_AncillaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PassengerMember_f94c408f-8076-43ff-b97e-7085bb3bdb5e" xlink:to="loc_sncy_AncillaryMember_b138ed8d-b507-46a9-b40d-3824ca038200" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CargoAndFreightMember_aab232a3-5c9a-412b-a3f8-1526cd396344" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CargoAndFreightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d64861af-5c34-4410-8201-edd0dfb94999" xlink:to="loc_us-gaap_CargoAndFreightMember_aab232a3-5c9a-412b-a3f8-1526cd396344" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceOtherMember_ce988aeb-b17b-47c7-aeb8-a2136de8c144" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ServiceOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d64861af-5c34-4410-8201-edd0dfb94999" xlink:to="loc_us-gaap_ServiceOtherMember_ce988aeb-b17b-47c7-aeb8-a2136de8c144" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_ff3a97eb-f1ce-410b-aa89-22f88e8c3e15" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_ae9a8b0f-16e3-45b7-bca5-bf891bdab95b" xlink:to="loc_srt_StatementGeographicalAxis_ff3a97eb-f1ce-410b-aa89-22f88e8c3e15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_ff3a97eb-f1ce-410b-aa89-22f88e8c3e15_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_ff3a97eb-f1ce-410b-aa89-22f88e8c3e15" xlink:to="loc_srt_SegmentGeographicalDomain_ff3a97eb-f1ce-410b-aa89-22f88e8c3e15_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_03ef8b81-20b1-48ee-b1a2-fbcf1f7a0bdb" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_ff3a97eb-f1ce-410b-aa89-22f88e8c3e15" xlink:to="loc_srt_SegmentGeographicalDomain_03ef8b81-20b1-48ee-b1a2-fbcf1f7a0bdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_9bb503f3-15e8-4ffc-be9d-b49caf796bc9" xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_03ef8b81-20b1-48ee-b1a2-fbcf1f7a0bdb" xlink:to="loc_country_US_9bb503f3-15e8-4ffc-be9d-b49caf796bc9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LatinAmericaMember_43cd476f-f3b1-4978-bc78-a646a624ca68" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LatinAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_03ef8b81-20b1-48ee-b1a2-fbcf1f7a0bdb" xlink:to="loc_srt_LatinAmericaMember_43cd476f-f3b1-4978-bc78-a646a624ca68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OtherCountriesMember_42eb3908-a6c5-4149-b47a-c4b478154fea" xlink:href="sncy-20221231.xsd#sncy_OtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_03ef8b81-20b1-48ee-b1a2-fbcf1f7a0bdb" xlink:to="loc_sncy_OtherCountriesMember_42eb3908-a6c5-4149-b47a-c4b478154fea" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/REVENUEContractBalancesDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#REVENUEContractBalancesDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/REVENUEContractBalancesDetails" xlink:type="extended" id="i3774cc9254fc4e6284e263f4b1862fb2_REVENUEContractBalancesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_a376bfdb-44bb-44d7-9b2c-91672166e16f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNet_c0a781ce-0f5c-4fb1-bfc8-ff3bd54692a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerAssetNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_a376bfdb-44bb-44d7-9b2c-91672166e16f" xlink:to="loc_us-gaap_ContractWithCustomerAssetNet_c0a781ce-0f5c-4fb1-bfc8-ff3bd54692a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_2a3eb67a-b02c-4289-80bb-5ca4fa1c7528" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_a376bfdb-44bb-44d7-9b2c-91672166e16f" xlink:to="loc_us-gaap_ContractWithCustomerLiability_2a3eb67a-b02c-4289-80bb-5ca4fa1c7528" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_5b70cb4c-405c-455b-a896-b8680ae49753" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_a376bfdb-44bb-44d7-9b2c-91672166e16f" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_5b70cb4c-405c-455b-a896-b8680ae49753" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_f1dd6251-e8bc-4c4d-b214-fd5c06aab9ab" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5b70cb4c-405c-455b-a896-b8680ae49753" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_f1dd6251-e8bc-4c4d-b214-fd5c06aab9ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_f1dd6251-e8bc-4c4d-b214-fd5c06aab9ab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_f1dd6251-e8bc-4c4d-b214-fd5c06aab9ab" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_f1dd6251-e8bc-4c4d-b214-fd5c06aab9ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3109937e-6ad0-4422-a938-3d8965de211c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_f1dd6251-e8bc-4c4d-b214-fd5c06aab9ab" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3109937e-6ad0-4422-a938-3d8965de211c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CostsToFulfillContractWithAmazonMember_a5d32259-ba6e-4324-a09b-52202a907d28" xlink:href="sncy-20221231.xsd#sncy_CostsToFulfillContractWithAmazonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3109937e-6ad0-4422-a938-3d8965de211c" xlink:to="loc_sncy_CostsToFulfillContractWithAmazonMember_a5d32259-ba6e-4324-a09b-52202a907d28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_45f21bda-bbb2-44b2-aee2-12aaae6bb0b2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5b70cb4c-405c-455b-a896-b8680ae49753" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_45f21bda-bbb2-44b2-aee2-12aaae6bb0b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_45f21bda-bbb2-44b2-aee2-12aaae6bb0b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_45f21bda-bbb2-44b2-aee2-12aaae6bb0b2" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_45f21bda-bbb2-44b2-aee2-12aaae6bb0b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_90ee4fd4-aec9-4dcf-9516-d9abe133676a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_45f21bda-bbb2-44b2-aee2-12aaae6bb0b2" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_90ee4fd4-aec9-4dcf-9516-d9abe133676a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AirTrafficLiabilitiesMember_5408bd2a-c3c7-43cb-8037-a0f85a72bdfb" xlink:href="sncy-20221231.xsd#sncy_AirTrafficLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_90ee4fd4-aec9-4dcf-9516-d9abe133676a" xlink:to="loc_sncy_AirTrafficLiabilitiesMember_5408bd2a-c3c7-43cb-8037-a0f85a72bdfb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_LoyaltyProgramLiabilitiesMember_180178f2-2f38-4f01-95f1-c25e8ca408e2" xlink:href="sncy-20221231.xsd#sncy_LoyaltyProgramLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_90ee4fd4-aec9-4dcf-9516-d9abe133676a" xlink:to="loc_sncy_LoyaltyProgramLiabilitiesMember_180178f2-2f38-4f01-95f1-c25e8ca408e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonDeferredStartUpCostsMember_8e2a4545-165c-410b-998d-78ee4f0785c6" xlink:href="sncy-20221231.xsd#sncy_AmazonDeferredStartUpCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_90ee4fd4-aec9-4dcf-9516-d9abe133676a" xlink:to="loc_sncy_AmazonDeferredStartUpCostsMember_8e2a4545-165c-410b-998d-78ee4f0785c6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/REVENUEAdditionalInformationDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#REVENUEAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/REVENUEAdditionalInformationDetails" xlink:type="extended" id="ie6d1f331c79d40278e75f5bbbb18c602_REVENUEAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CostIncurredToGetCargoAircraftsReadyForServiceNumberAmortizationPeriod_ce00b152-6c45-4c1e-899e-5a70ab434a64" xlink:href="sncy-20221231.xsd#sncy_CostIncurredToGetCargoAircraftsReadyForServiceNumberAmortizationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:to="loc_sncy_CostIncurredToGetCargoAircraftsReadyForServiceNumberAmortizationPeriod_ce00b152-6c45-4c1e-899e-5a70ab434a64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ProceedsFromStartUpCostsReceived_dfb70766-a575-4a15-a995-e1e17ab35f26" xlink:href="sncy-20221231.xsd#sncy_ProceedsFromStartUpCostsReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:to="loc_sncy_ProceedsFromStartUpCostsReceived_dfb70766-a575-4a15-a995-e1e17ab35f26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsVestedDuringPeriod_c5a2f381-150c-4132-8fa4-95da428b8176" xlink:href="sncy-20221231.xsd#sncy_WarrantsVestedDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:to="loc_sncy_WarrantsVestedDuringPeriod_c5a2f381-150c-4132-8fa4-95da428b8176" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_WarrantsVestedFairValue_95179d2a-0807-4cce-86cc-844b54a6f560" xlink:href="sncy-20221231.xsd#sncy_WarrantsVestedFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:to="loc_sncy_WarrantsVestedFairValue_95179d2a-0807-4cce-86cc-844b54a6f560" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_1bdffc01-d802-4fbf-ac48-010eb4f9eb88" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_1bdffc01-d802-4fbf-ac48-010eb4f9eb88" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_907a0ca0-d3d5-45e2-9820-144871871698" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_907a0ca0-d3d5-45e2-9820-144871871698" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_a7b6d1d4-7db4-45ed-9a9f-ef432aa44b7e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d94b0fc-034c-4395-9de2-520da75ab54b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_a7b6d1d4-7db4-45ed-9a9f-ef432aa44b7e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_102acf8c-0c76-4b9e-bfdf-a8d4ca5a48a3" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_a7b6d1d4-7db4-45ed-9a9f-ef432aa44b7e" xlink:to="loc_srt_ProductOrServiceAxis_102acf8c-0c76-4b9e-bfdf-a8d4ca5a48a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_102acf8c-0c76-4b9e-bfdf-a8d4ca5a48a3_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_102acf8c-0c76-4b9e-bfdf-a8d4ca5a48a3" xlink:to="loc_srt_ProductsAndServicesDomain_102acf8c-0c76-4b9e-bfdf-a8d4ca5a48a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6f10f145-4d6a-4d6d-a592-ecdd2c48aca4" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_102acf8c-0c76-4b9e-bfdf-a8d4ca5a48a3" xlink:to="loc_srt_ProductsAndServicesDomain_6f10f145-4d6a-4d6d-a592-ecdd2c48aca4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CargoAndFreightMember_aafd789c-048a-4d4e-81b8-07f60dfb32d0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CargoAndFreightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6f10f145-4d6a-4d6d-a592-ecdd2c48aca4" xlink:to="loc_us-gaap_CargoAndFreightMember_aafd789c-048a-4d4e-81b8-07f60dfb32d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassengerMember_b97ee3bf-b080-48eb-805d-5526d75631a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PassengerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6f10f145-4d6a-4d6d-a592-ecdd2c48aca4" xlink:to="loc_us-gaap_PassengerMember_b97ee3bf-b080-48eb-805d-5526d75631a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_be21707f-f4ff-4a0f-95eb-3a2626f55d3c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_a7b6d1d4-7db4-45ed-9a9f-ef432aa44b7e" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_be21707f-f4ff-4a0f-95eb-3a2626f55d3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_be21707f-f4ff-4a0f-95eb-3a2626f55d3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_be21707f-f4ff-4a0f-95eb-3a2626f55d3c" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_be21707f-f4ff-4a0f-95eb-3a2626f55d3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_eb9bced9-374d-47e6-b25c-69776850c6f4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_be21707f-f4ff-4a0f-95eb-3a2626f55d3c" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_eb9bced9-374d-47e6-b25c-69776850c6f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AirTrafficLiabilitiesMember_cfb30075-867c-429e-b5d7-18cd1895aae6" xlink:href="sncy-20221231.xsd#sncy_AirTrafficLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_eb9bced9-374d-47e6-b25c-69776850c6f4" xlink:to="loc_sncy_AirTrafficLiabilitiesMember_cfb30075-867c-429e-b5d7-18cd1895aae6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonDeferredStartUpCostsMember_66f5874c-9aac-4b34-8ffa-ef069d857400" xlink:href="sncy-20221231.xsd#sncy_AmazonDeferredStartUpCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_eb9bced9-374d-47e6-b25c-69776850c6f4" xlink:to="loc_sncy_AmazonDeferredStartUpCostsMember_66f5874c-9aac-4b34-8ffa-ef069d857400" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_03676ca9-19d3-4d3b-90cf-0b9d303c23da" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_a7b6d1d4-7db4-45ed-9a9f-ef432aa44b7e" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_03676ca9-19d3-4d3b-90cf-0b9d303c23da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_03676ca9-19d3-4d3b-90cf-0b9d303c23da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_03676ca9-19d3-4d3b-90cf-0b9d303c23da" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_03676ca9-19d3-4d3b-90cf-0b9d303c23da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_b8a6980a-5331-4ff5-950c-76ea48e7085c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_03676ca9-19d3-4d3b-90cf-0b9d303c23da" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_b8a6980a-5331-4ff5-950c-76ea48e7085c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesMember_b433968e-9cdc-4ca9-b9be-a99a6f702981" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_b8a6980a-5331-4ff5-950c-76ea48e7085c" xlink:to="loc_us-gaap_OtherLiabilitiesMember_b433968e-9cdc-4ca9-b9be-a99a6f702981" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_f612390c-2ac1-46b8-ac90-1fdda1438fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_a7b6d1d4-7db4-45ed-9a9f-ef432aa44b7e" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_f612390c-2ac1-46b8-ac90-1fdda1438fb0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_f612390c-2ac1-46b8-ac90-1fdda1438fb0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_f612390c-2ac1-46b8-ac90-1fdda1438fb0" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_f612390c-2ac1-46b8-ac90-1fdda1438fb0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_db2db22a-d932-4e78-93dd-21ead1b639f6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_f612390c-2ac1-46b8-ac90-1fdda1438fb0" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_db2db22a-d932-4e78-93dd-21ead1b639f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CostsToFulfillContractWithAmazonMember_d1a20e57-3819-40a0-b21a-b8cb96f6dd32" xlink:href="sncy-20221231.xsd#sncy_CostsToFulfillContractWithAmazonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_db2db22a-d932-4e78-93dd-21ead1b639f6" xlink:to="loc_sncy_CostsToFulfillContractWithAmazonMember_d1a20e57-3819-40a0-b21a-b8cb96f6dd32" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/REVENUELoyaltyProgramDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#REVENUELoyaltyProgramDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/REVENUELoyaltyProgramDetails" xlink:type="extended" id="ife8137b3cafa4bfeac6a5901f496cf99_REVENUELoyaltyProgramDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_bb651e24-1044-4ec0-9590-39ec71b2584d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ChangeInContractWithCustomerLiabilityRollForward_42368fb9-b63f-4fc4-961b-96710cb8b56d" xlink:href="sncy-20221231.xsd#sncy_ChangeInContractWithCustomerLiabilityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_bb651e24-1044-4ec0-9590-39ec71b2584d" xlink:to="loc_sncy_ChangeInContractWithCustomerLiabilityRollForward_42368fb9-b63f-4fc4-961b-96710cb8b56d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_ddbc718a-0d6a-4ec7-bdbf-2f7900d39093" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_ChangeInContractWithCustomerLiabilityRollForward_42368fb9-b63f-4fc4-961b-96710cb8b56d" xlink:to="loc_us-gaap_ContractWithCustomerLiability_ddbc718a-0d6a-4ec7-bdbf-2f7900d39093" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ContractWithCustomerLiabilityIncreaseFromLoyaltyPointsEarned_00bc42fc-9e75-42ae-8613-092c3094505c" xlink:href="sncy-20221231.xsd#sncy_ContractWithCustomerLiabilityIncreaseFromLoyaltyPointsEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_ChangeInContractWithCustomerLiabilityRollForward_42368fb9-b63f-4fc4-961b-96710cb8b56d" xlink:to="loc_sncy_ContractWithCustomerLiabilityIncreaseFromLoyaltyPointsEarned_00bc42fc-9e75-42ae-8613-092c3094505c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_bed40d00-b54b-4af7-bdf1-a25aa74d2c91" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_ChangeInContractWithCustomerLiabilityRollForward_42368fb9-b63f-4fc4-961b-96710cb8b56d" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_bed40d00-b54b-4af7-bdf1-a25aa74d2c91" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_dc304909-f96b-400b-b9e2-a5807458eeda" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_7af569ca-6fd2-495e-970a-5aed4028e418" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_bb651e24-1044-4ec0-9590-39ec71b2584d" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_7af569ca-6fd2-495e-970a-5aed4028e418" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_f8227a12-383d-428f-aefb-477497f4f825" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_7af569ca-6fd2-495e-970a-5aed4028e418" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_f8227a12-383d-428f-aefb-477497f4f825" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_f8227a12-383d-428f-aefb-477497f4f825_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_f8227a12-383d-428f-aefb-477497f4f825" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_f8227a12-383d-428f-aefb-477497f4f825_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_87f55375-811d-495f-8be6-9161c3c5c882" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_f8227a12-383d-428f-aefb-477497f4f825" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_87f55375-811d-495f-8be6-9161c3c5c882" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_LoyaltyProgramLiabilitiesMember_2a28f6ad-5224-4245-b59c-4c8f82900f83" xlink:href="sncy-20221231.xsd#sncy_LoyaltyProgramLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_87f55375-811d-495f-8be6-9161c3c5c882" xlink:to="loc_sncy_LoyaltyProgramLiabilitiesMember_2a28f6ad-5224-4245-b59c-4c8f82900f83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AirTrafficLiabilitiesMember_aaf0c8c5-2a6a-49a1-acaf-de2968f8c6de" xlink:href="sncy-20221231.xsd#sncy_AirTrafficLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_87f55375-811d-495f-8be6-9161c3c5c882" xlink:to="loc_sncy_AirTrafficLiabilitiesMember_aaf0c8c5-2a6a-49a1-acaf-de2968f8c6de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmazonDeferredStartUpCostsMember_6353618e-71f7-4be3-9bf2-5c4996de9956" xlink:href="sncy-20221231.xsd#sncy_AmazonDeferredStartUpCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_87f55375-811d-495f-8be6-9161c3c5c882" xlink:to="loc_sncy_AmazonDeferredStartUpCostsMember_6353618e-71f7-4be3-9bf2-5c4996de9956" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/EARNINGSPERSHAREComputationofbasicanddilutedearningsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#EARNINGSPERSHAREComputationofbasicanddilutedearningsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/EARNINGSPERSHAREComputationofbasicanddilutedearningsDetails" xlink:type="extended" id="i1299a86c8186438587b12a6d5b1c4983_EARNINGSPERSHAREComputationofbasicanddilutedearningsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fe3d23ec-26b1-464c-bef2-eb2958bc666f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_70273f1a-927d-4f97-89f7-1640b08f2095" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fe3d23ec-26b1-464c-bef2-eb2958bc666f" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_70273f1a-927d-4f97-89f7-1640b08f2095" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PercentageOfStockOptionsExpectedToMeetPerformanceConditions_727940c1-4318-47e5-8023-d17b75f5dcb7" xlink:href="sncy-20221231.xsd#sncy_PercentageOfStockOptionsExpectedToMeetPerformanceConditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fe3d23ec-26b1-464c-bef2-eb2958bc666f" xlink:to="loc_sncy_PercentageOfStockOptionsExpectedToMeetPerformanceConditions_727940c1-4318-47e5-8023-d17b75f5dcb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_181c0397-924e-491c-9eb4-4f0f69273090" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fe3d23ec-26b1-464c-bef2-eb2958bc666f" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_181c0397-924e-491c-9eb4-4f0f69273090" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_8b68bdf3-a83d-45c4-8193-7284ff5c1728" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fe3d23ec-26b1-464c-bef2-eb2958bc666f" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_8b68bdf3-a83d-45c4-8193-7284ff5c1728" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_ee1e4206-5b9c-4b9e-84f4-84f1192c3857" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_8b68bdf3-a83d-45c4-8193-7284ff5c1728" xlink:to="loc_us-gaap_AwardTypeAxis_ee1e4206-5b9c-4b9e-84f4-84f1192c3857" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ee1e4206-5b9c-4b9e-84f4-84f1192c3857_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_ee1e4206-5b9c-4b9e-84f4-84f1192c3857" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ee1e4206-5b9c-4b9e-84f4-84f1192c3857_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f8675966-7ca1-4dff-843b-8f9afc7bb226" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_ee1e4206-5b9c-4b9e-84f4-84f1192c3857" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f8675966-7ca1-4dff-843b-8f9afc7bb226" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PerformanceBasedStockOptionsMember_0072af0c-75d2-4018-9dd9-1ee112639eb6" xlink:href="sncy-20221231.xsd#sncy_PerformanceBasedStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f8675966-7ca1-4dff-843b-8f9afc7bb226" xlink:to="loc_sncy_PerformanceBasedStockOptionsMember_0072af0c-75d2-4018-9dd9-1ee112639eb6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/AIRCRAFTAircraftfleetDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#AIRCRAFTAircraftfleetDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/AIRCRAFTAircraftfleetDetails" xlink:type="extended" id="i9c2e8c6812b541e0ae9c81b03d97a6c0_AIRCRAFTAircraftfleetDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PropertyPlantAndEquipmentNumberOfAircraftOutstanding_69243d78-1814-44f8-9e47-55ef786378e3" xlink:href="sncy-20221231.xsd#sncy_PropertyPlantAndEquipmentNumberOfAircraftOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_PropertyPlantAndEquipmentNumberOfAircraftOutstanding_69243d78-1814-44f8-9e47-55ef786378e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftsPurchased_82aae78f-c7c8-4314-824f-aca4bce82f60" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftsPurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfAircraftsPurchased_82aae78f-c7c8-4314-824f-aca4bce82f60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PropertyPlantAndEquipmentNumberOfAircraftReclassified_2028e3ac-e189-4666-8354-1cc2eda9275c" xlink:href="sncy-20221231.xsd#sncy_PropertyPlantAndEquipmentNumberOfAircraftReclassified"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_PropertyPlantAndEquipmentNumberOfAircraftReclassified_2028e3ac-e189-4666-8354-1cc2eda9275c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNumberOfAircraftSold_280e457a-532a-42d3-8dd6-cbde8a9e593e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentNumberOfAircraftSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNumberOfAircraftSold_280e457a-532a-42d3-8dd6-cbde8a9e593e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PropertyPlantAndEquipmentNumberOfAircraftOutstanding_62624c35-601e-4f66-ba29-2b55be1fb6a7" xlink:href="sncy-20221231.xsd#sncy_PropertyPlantAndEquipmentNumberOfAircraftOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfNewAircraftsPurchased_c53b37e5-d8b1-4255-bd34-a42ecae6c017" xlink:href="sncy-20221231.xsd#sncy_NumberOfNewAircraftsPurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfNewAircraftsPurchased_c53b37e5-d8b1-4255-bd34-a42ecae6c017" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftsFinancedUsingFinanceLeaseArrangement_982c3995-0e77-41b3-a786-6f35174d64c7" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftsFinancedUsingFinanceLeaseArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfAircraftsFinancedUsingFinanceLeaseArrangement_982c3995-0e77-41b3-a786-6f35174d64c7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftsFinanced_78a9356e-8d0c-4a2e-aa14-9ddfb3848151" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftsFinanced"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfAircraftsFinanced_78a9356e-8d0c-4a2e-aa14-9ddfb3848151" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftsUnencumbered_91793214-e4c5-4229-873d-bf7cb9cfc28b" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftsUnencumbered"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfAircraftsUnencumbered_91793214-e4c5-4229-873d-bf7cb9cfc28b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftsTransferredFromOperatingToFinanceLease_954828b3-1a06-4edc-a8e7-0ee45f51c046" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftsTransferredFromOperatingToFinanceLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfAircraftsTransferredFromOperatingToFinanceLease_954828b3-1a06-4edc-a8e7-0ee45f51c046" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftFinanceLeasePurchaseOptionsExercised_01fa9cd7-4936-482b-b696-1a705a301841" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftFinanceLeasePurchaseOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfAircraftFinanceLeasePurchaseOptionsExercised_01fa9cd7-4936-482b-b696-1a705a301841" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_d77bee6e-3e54-4fa6-856b-8ae505a3e4ef" xlink:href="sncy-20221231.xsd#sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_d77bee6e-3e54-4fa6-856b-8ae505a3e4ef" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_15cceaa3-e717-4618-ba87-4bee77b61b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9d467dc9-0fc9-44c7-b95b-bf3176647371" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_15cceaa3-e717-4618-ba87-4bee77b61b8f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AircraftTypeAxis_cb25d2be-06cd-414f-9c1b-a96f11db2e21" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_AircraftTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_15cceaa3-e717-4618-ba87-4bee77b61b8f" xlink:to="loc_srt_AircraftTypeAxis_cb25d2be-06cd-414f-9c1b-a96f11db2e21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AircraftTypeMember_cb25d2be-06cd-414f-9c1b-a96f11db2e21_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_AircraftTypeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_AircraftTypeAxis_cb25d2be-06cd-414f-9c1b-a96f11db2e21" xlink:to="loc_srt_AircraftTypeMember_cb25d2be-06cd-414f-9c1b-a96f11db2e21_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AircraftTypeMember_b69ee0cb-82d8-410d-9d6e-cbfe407e29c5" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_AircraftTypeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_AircraftTypeAxis_cb25d2be-06cd-414f-9c1b-a96f11db2e21" xlink:to="loc_srt_AircraftTypeMember_b69ee0cb-82d8-410d-9d6e-cbfe407e29c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_B737800Member_f8508673-3efd-4f9d-b977-35c352db8167" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_B737800Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AircraftTypeMember_b69ee0cb-82d8-410d-9d6e-cbfe407e29c5" xlink:to="loc_srt_B737800Member_f8508673-3efd-4f9d-b977-35c352db8167" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_B737700Member_f0c8a399-5783-42bb-9ba7-ccd2e7d6a405" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_B737700Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AircraftTypeMember_b69ee0cb-82d8-410d-9d6e-cbfe407e29c5" xlink:to="loc_srt_B737700Member_f0c8a399-5783-42bb-9ba7-ccd2e7d6a405" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassengerMember_3d4fb4db-7468-43c6-bc0f-21a929206f1f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PassengerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AircraftTypeMember_b69ee0cb-82d8-410d-9d6e-cbfe407e29c5" xlink:to="loc_us-gaap_PassengerMember_3d4fb4db-7468-43c6-bc0f-21a929206f1f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CargoMember_36323149-b507-4122-83fb-55e12556d8c7" xlink:href="sncy-20221231.xsd#sncy_CargoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AircraftTypeMember_b69ee0cb-82d8-410d-9d6e-cbfe407e29c5" xlink:to="loc_sncy_CargoMember_36323149-b507-4122-83fb-55e12556d8c7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_86c2b2c4-c85f-4a91-ba55-f1c614e69390" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_15cceaa3-e717-4618-ba87-4bee77b61b8f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_86c2b2c4-c85f-4a91-ba55-f1c614e69390" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_86c2b2c4-c85f-4a91-ba55-f1c614e69390_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_86c2b2c4-c85f-4a91-ba55-f1c614e69390" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_86c2b2c4-c85f-4a91-ba55-f1c614e69390_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a172ca99-f0c0-4d90-8f37-259d76bc5326" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_86c2b2c4-c85f-4a91-ba55-f1c614e69390" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a172ca99-f0c0-4d90-8f37-259d76bc5326" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OwnedAircraftsMember_6368c645-7afe-4370-8896-3fc3738d546f" xlink:href="sncy-20221231.xsd#sncy_OwnedAircraftsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a172ca99-f0c0-4d90-8f37-259d76bc5326" xlink:to="loc_sncy_OwnedAircraftsMember_6368c645-7afe-4370-8896-3fc3738d546f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftsUnderFinanceLeasesMember_5206d4bb-72f5-477e-a620-1df99fa0e1f2" xlink:href="sncy-20221231.xsd#sncy_AircraftsUnderFinanceLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a172ca99-f0c0-4d90-8f37-259d76bc5326" xlink:to="loc_sncy_AircraftsUnderFinanceLeasesMember_5206d4bb-72f5-477e-a620-1df99fa0e1f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftsUnderOperatingLeasesMember_65c662f4-3234-4e1e-b981-e3c923f94f13" xlink:href="sncy-20221231.xsd#sncy_AircraftsUnderOperatingLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a172ca99-f0c0-4d90-8f37-259d76bc5326" xlink:to="loc_sncy_AircraftsUnderOperatingLeasesMember_65c662f4-3234-4e1e-b981-e3c923f94f13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftsOperatedForAmazonMember_4595f3db-14d8-4187-9eea-6ede3bd1e7b4" xlink:href="sncy-20221231.xsd#sncy_AircraftsOperatedForAmazonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a172ca99-f0c0-4d90-8f37-259d76bc5326" xlink:to="loc_sncy_AircraftsOperatedForAmazonMember_4595f3db-14d8-4187-9eea-6ede3bd1e7b4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/AIRCRAFTDepreciationAmortizationandRentExpenseonAircraftDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#AIRCRAFTDepreciationAmortizationandRentExpenseonAircraftDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/AIRCRAFTDepreciationAmortizationandRentExpenseonAircraftDetails" xlink:type="extended" id="if2338c0a01084e72863d7dcbec28c54a_AIRCRAFTDepreciationAmortizationandRentExpenseonAircraftDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9051f163-c6f5-4c03-bce2-d75953920135" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_99c1c683-f32c-4296-b4ee-2c77f879854a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9051f163-c6f5-4c03-bce2-d75953920135" xlink:to="loc_us-gaap_Depreciation_99c1c683-f32c-4296-b4ee-2c77f879854a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_74f91dae-df63-43ba-befe-38ec7c546d85" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9051f163-c6f5-4c03-bce2-d75953920135" xlink:to="loc_us-gaap_AdjustmentForAmortization_74f91dae-df63-43ba-befe-38ec7c546d85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AircraftRental_7c7ab7e6-2831-45b0-ba77-c71680cf196f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AircraftRental"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9051f163-c6f5-4c03-bce2-d75953920135" xlink:to="loc_us-gaap_AircraftRental_7c7ab7e6-2831-45b0-ba77-c71680cf196f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DepreciationAmortizationAndRentalExpenses_ecf6b20e-0165-46b0-bb0e-5463ab643f5e" xlink:href="sncy-20221231.xsd#sncy_DepreciationAmortizationAndRentalExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9051f163-c6f5-4c03-bce2-d75953920135" xlink:to="loc_sncy_DepreciationAmortizationAndRentalExpenses_ecf6b20e-0165-46b0-bb0e-5463ab643f5e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_63da2a22-5e43-4c1b-a141-b2a364531cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9051f163-c6f5-4c03-bce2-d75953920135" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_63da2a22-5e43-4c1b-a141-b2a364531cb5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_912c3229-cf01-41df-8fc1-d468f116a375" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_63da2a22-5e43-4c1b-a141-b2a364531cb5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_912c3229-cf01-41df-8fc1-d468f116a375" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_912c3229-cf01-41df-8fc1-d468f116a375_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_912c3229-cf01-41df-8fc1-d468f116a375" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_912c3229-cf01-41df-8fc1-d468f116a375_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_516edc0d-cbef-4d5c-9bf8-d553aed9b449" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_912c3229-cf01-41df-8fc1-d468f116a375" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_516edc0d-cbef-4d5c-9bf8-d553aed9b449" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OwnedAircraftsMember_4d3a311e-00d7-497b-a08e-913e6d652fda" xlink:href="sncy-20221231.xsd#sncy_OwnedAircraftsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_516edc0d-cbef-4d5c-9bf8-d553aed9b449" xlink:to="loc_sncy_OwnedAircraftsMember_4d3a311e-00d7-497b-a08e-913e6d652fda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftsUnderOperatingLeasesMember_e6a74d01-1fb2-45fd-9050-64672f046f3c" xlink:href="sncy-20221231.xsd#sncy_AircraftsUnderOperatingLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_516edc0d-cbef-4d5c-9bf8-d553aed9b449" xlink:to="loc_sncy_AircraftsUnderOperatingLeasesMember_e6a74d01-1fb2-45fd-9050-64672f046f3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftsUnderFinanceLeasesMember_6bb65be7-6353-4168-bbd1-c9a047ca4e76" xlink:href="sncy-20221231.xsd#sncy_AircraftsUnderFinanceLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_516edc0d-cbef-4d5c-9bf8-d553aed9b449" xlink:to="loc_sncy_AircraftsUnderFinanceLeasesMember_6bb65be7-6353-4168-bbd1-c9a047ca4e76" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/AIRCRAFTAircraftMaintenanceDepositsContraAssetsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#AIRCRAFTAircraftMaintenanceDepositsContraAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/AIRCRAFTAircraftMaintenanceDepositsContraAssetsDetails" xlink:type="extended" id="ie5da1cd886024929a9f9d2033ffa5e55_AIRCRAFTAircraftMaintenanceDepositsContraAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4f887e05-4485-4567-8cb8-46a49aba9ded" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ContraAssetsOutstanding_a18fda95-eed8-4b26-a390-9f59b138df50" xlink:href="sncy-20221231.xsd#sncy_ContraAssetsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4f887e05-4485-4567-8cb8-46a49aba9ded" xlink:to="loc_sncy_ContraAssetsOutstanding_a18fda95-eed8-4b26-a390-9f59b138df50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_IncreaseDecreaseInContraAssets_6c34335a-8f2d-48fe-9ee0-fbe831d93513" xlink:href="sncy-20221231.xsd#sncy_IncreaseDecreaseInContraAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4f887e05-4485-4567-8cb8-46a49aba9ded" xlink:to="loc_sncy_IncreaseDecreaseInContraAssets_6c34335a-8f2d-48fe-9ee0-fbe831d93513" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_0dbc831f-0717-46b7-82b5-1348722456ff" xlink:href="sncy-20221231.xsd#sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4f887e05-4485-4567-8cb8-46a49aba9ded" xlink:to="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_0dbc831f-0717-46b7-82b5-1348722456ff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_57cb7e5e-0607-41f9-bf66-7d1c105adefc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4f887e05-4485-4567-8cb8-46a49aba9ded" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_57cb7e5e-0607-41f9-bf66-7d1c105adefc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_1357aac7-06f1-4f55-ab8b-e612ab54b168" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_57cb7e5e-0607-41f9-bf66-7d1c105adefc" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_1357aac7-06f1-4f55-ab8b-e612ab54b168" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1357aac7-06f1-4f55-ab8b-e612ab54b168_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_1357aac7-06f1-4f55-ab8b-e612ab54b168" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1357aac7-06f1-4f55-ab8b-e612ab54b168_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_7eeb33e8-0818-4cbc-97fe-6b8b923385fa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_1357aac7-06f1-4f55-ab8b-e612ab54b168" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_7eeb33e8-0818-4cbc-97fe-6b8b923385fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftMaintenanceDepositsContraAssetsMember_1307a679-9f64-48b1-8a4d-e8b7e11790dd" xlink:href="sncy-20221231.xsd#sncy_AircraftMaintenanceDepositsContraAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_7eeb33e8-0818-4cbc-97fe-6b8b923385fa" xlink:to="loc_sncy_AircraftMaintenanceDepositsContraAssetsMember_1307a679-9f64-48b1-8a4d-e8b7e11790dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3c2808ab-f4fc-4739-8033-e589f98e5377" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_57cb7e5e-0607-41f9-bf66-7d1c105adefc" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3c2808ab-f4fc-4739-8033-e589f98e5377" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3c2808ab-f4fc-4739-8033-e589f98e5377_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3c2808ab-f4fc-4739-8033-e589f98e5377" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3c2808ab-f4fc-4739-8033-e589f98e5377_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_7c4c764c-6545-47ba-92e5-07f4ae6aabb5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3c2808ab-f4fc-4739-8033-e589f98e5377" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_7c4c764c-6545-47ba-92e5-07f4ae6aabb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OwnedAircraftsMember_ccb5ee64-719d-44d6-8430-dbf675a664bf" xlink:href="sncy-20221231.xsd#sncy_OwnedAircraftsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_7c4c764c-6545-47ba-92e5-07f4ae6aabb5" xlink:to="loc_sncy_OwnedAircraftsMember_ccb5ee64-719d-44d6-8430-dbf675a664bf" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/AIRCRAFTOvermarketLiabilitiesDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#AIRCRAFTOvermarketLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/AIRCRAFTOvermarketLiabilitiesDetails" xlink:type="extended" id="i243a25c8b0c8470eaabedaa123611ec7_AIRCRAFTOvermarketLiabilitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ContraAssetsOutstanding_daf8c99f-8282-4740-8757-8046406f3306" xlink:href="sncy-20221231.xsd#sncy_ContraAssetsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_ContraAssetsOutstanding_daf8c99f-8282-4740-8757-8046406f3306" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftsTransferredFromOperatingToFinanceLease_ffd0bb0c-8b99-4704-9589-c8703fa2497b" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftsTransferredFromOperatingToFinanceLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_NumberOfAircraftsTransferredFromOperatingToFinanceLease_ffd0bb0c-8b99-4704-9589-c8703fa2497b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_LeaseModificationAmountReclassifiedToFinanceLeaseRightOfUseAsset_b72bbceb-8c72-48fa-a8ff-93b5e57be575" xlink:href="sncy-20221231.xsd#sncy_LeaseModificationAmountReclassifiedToFinanceLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_LeaseModificationAmountReclassifiedToFinanceLeaseRightOfUseAsset_b72bbceb-8c72-48fa-a8ff-93b5e57be575" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DecreaseInContraAssetsRelatingToPurchaseOfAircraftsPreviouslyLeased_f2aec777-cdbd-4af2-8c34-b555f3eda91a" xlink:href="sncy-20221231.xsd#sncy_DecreaseInContraAssetsRelatingToPurchaseOfAircraftsPreviouslyLeased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_DecreaseInContraAssetsRelatingToPurchaseOfAircraftsPreviouslyLeased_f2aec777-cdbd-4af2-8c34-b555f3eda91a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_7b4484f5-db4b-4269-9e5a-7e671c0322f7" xlink:href="sncy-20221231.xsd#sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_7b4484f5-db4b-4269-9e5a-7e671c0322f7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OverMarketLiabilities_689cc54b-b6fb-48ea-97cc-de12b52d5dcf" xlink:href="sncy-20221231.xsd#sncy_OverMarketLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_OverMarketLiabilities_689cc54b-b6fb-48ea-97cc-de12b52d5dcf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_IncreaseDecreaseInOverMarketMaintenanceReserveLiabilities_81486eb9-7823-468e-9427-174b271e984d" xlink:href="sncy-20221231.xsd#sncy_IncreaseDecreaseInOverMarketMaintenanceReserveLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_IncreaseDecreaseInOverMarketMaintenanceReserveLiabilities_81486eb9-7823-468e-9427-174b271e984d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OverMarketMaintenanceReserveLiabilitiesPurchaseOfAircraft_b6cefa1f-78c8-435e-aea3-33a12829da3a" xlink:href="sncy-20221231.xsd#sncy_OverMarketMaintenanceReserveLiabilitiesPurchaseOfAircraft"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_sncy_OverMarketMaintenanceReserveLiabilitiesPurchaseOfAircraft_b6cefa1f-78c8-435e-aea3-33a12829da3a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35a248af-40b3-4a1d-a1b6-9b678b4754dd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_c68fd00d-d575-4ab2-af26-4b03f84d000f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35a248af-40b3-4a1d-a1b6-9b678b4754dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_031c8e4e-f2df-47fa-b575-d439d58dc846" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35a248af-40b3-4a1d-a1b6-9b678b4754dd" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_031c8e4e-f2df-47fa-b575-d439d58dc846" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_031c8e4e-f2df-47fa-b575-d439d58dc846_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_031c8e4e-f2df-47fa-b575-d439d58dc846" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_031c8e4e-f2df-47fa-b575-d439d58dc846_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_5fd1168b-5f82-4986-9c3a-832264cfac90" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_031c8e4e-f2df-47fa-b575-d439d58dc846" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_5fd1168b-5f82-4986-9c3a-832264cfac90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OverMarketLeaseRatesContraAssetsIncludedInOperatingLeaseRightOfUseAssetsMember_0b85b69e-b29f-43d9-b384-b592e8c3d30e" xlink:href="sncy-20221231.xsd#sncy_OverMarketLeaseRatesContraAssetsIncludedInOperatingLeaseRightOfUseAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_5fd1168b-5f82-4986-9c3a-832264cfac90" xlink:to="loc_sncy_OverMarketLeaseRatesContraAssetsIncludedInOperatingLeaseRightOfUseAssetsMember_0b85b69e-b29f-43d9-b384-b592e8c3d30e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AircraftTypeAxis_6eb53066-86e6-4648-95b2-7b325dbf162e" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_AircraftTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35a248af-40b3-4a1d-a1b6-9b678b4754dd" xlink:to="loc_srt_AircraftTypeAxis_6eb53066-86e6-4648-95b2-7b325dbf162e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AircraftTypeMember_6eb53066-86e6-4648-95b2-7b325dbf162e_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_AircraftTypeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_AircraftTypeAxis_6eb53066-86e6-4648-95b2-7b325dbf162e" xlink:to="loc_srt_AircraftTypeMember_6eb53066-86e6-4648-95b2-7b325dbf162e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AircraftTypeMember_4c4369c3-bf33-401e-bcd8-deba7467a484" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_AircraftTypeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_AircraftTypeAxis_6eb53066-86e6-4648-95b2-7b325dbf162e" xlink:to="loc_srt_AircraftTypeMember_4c4369c3-bf33-401e-bcd8-deba7467a484" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassengerMember_1058e6ea-7700-4a42-8888-72b42ed5da7a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PassengerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AircraftTypeMember_4c4369c3-bf33-401e-bcd8-deba7467a484" xlink:to="loc_us-gaap_PassengerMember_1058e6ea-7700-4a42-8888-72b42ed5da7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b9d4c78d-7612-417b-996e-94f534dc7c71" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35a248af-40b3-4a1d-a1b6-9b678b4754dd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b9d4c78d-7612-417b-996e-94f534dc7c71" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b9d4c78d-7612-417b-996e-94f534dc7c71_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b9d4c78d-7612-417b-996e-94f534dc7c71" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b9d4c78d-7612-417b-996e-94f534dc7c71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_251f6d0e-7c07-4982-850e-5c78e1aa7cdb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b9d4c78d-7612-417b-996e-94f534dc7c71" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_251f6d0e-7c07-4982-850e-5c78e1aa7cdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OwnedAircraftsMember_9a624130-421b-4a5b-a968-ef0fae1e0099" xlink:href="sncy-20221231.xsd#sncy_OwnedAircraftsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_251f6d0e-7c07-4982-850e-5c78e1aa7cdb" xlink:to="loc_sncy_OwnedAircraftsMember_9a624130-421b-4a5b-a968-ef0fae1e0099" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/GOODWILLANDOTHERINTANGIBLEASSETSComponentsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#GOODWILLANDOTHERINTANGIBLEASSETSComponentsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/GOODWILLANDOTHERINTANGIBLEASSETSComponentsDetails" xlink:type="extended" id="i1a982bb622a94a4e8319af5b44894abb_GOODWILLANDOTHERINTANGIBLEASSETSComponentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_1a39aa45-81c8-4d06-9fc0-8266e305cba4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:to="loc_us-gaap_Goodwill_1a39aa45-81c8-4d06-9fc0-8266e305cba4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_82349bd6-8f47-46dd-86bb-f5581c8762f3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_82349bd6-8f47-46dd-86bb-f5581c8762f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_8d3467a0-0598-4488-ac25-ceadb11e02d2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_82349bd6-8f47-46dd-86bb-f5581c8762f3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_8d3467a0-0598-4488-ac25-ceadb11e02d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_d6d3b9e7-0f8c-4c8f-8055-4e383ea2627f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_82349bd6-8f47-46dd-86bb-f5581c8762f3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_d6d3b9e7-0f8c-4c8f-8055-4e383ea2627f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_b3853230-2e10-411c-b508-ecbd3313e1fc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_82349bd6-8f47-46dd-86bb-f5581c8762f3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_b3853230-2e10-411c-b508-ecbd3313e1fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwillAbstract_6365c01d-4e1a-4092-b37a-f617624bff7b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwillAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwillAbstract_6365c01d-4e1a-4092-b37a-f617624bff7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_3d3883e0-7cf9-4d8f-9858-98a3a8ced056" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsNetExcludingGoodwillAbstract_6365c01d-4e1a-4092-b37a-f617624bff7b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_3d3883e0-7cf9-4d8f-9858-98a3a8ced056" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwillAbstract_e7cecece-62f9-496e-a892-b3dc25a80adc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwillAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwillAbstract_e7cecece-62f9-496e-a892-b3dc25a80adc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_7cbd3111-7355-47c2-9f06-a9814337f07c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwillAbstract_e7cecece-62f9-496e-a892-b3dc25a80adc" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_7cbd3111-7355-47c2-9f06-a9814337f07c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_3bc4a743-04a6-4a9d-9f1d-1dc40daef74b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwillAbstract_e7cecece-62f9-496e-a892-b3dc25a80adc" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_3bc4a743-04a6-4a9d-9f1d-1dc40daef74b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_IntangibleAssetsNetIncludingGoodWillGross_0c706727-d291-4963-8055-d9a313d7eae1" xlink:href="sncy-20221231.xsd#sncy_IntangibleAssetsNetIncludingGoodWillGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:to="loc_sncy_IntangibleAssetsNetIncludingGoodWillGross_0c706727-d291-4963-8055-d9a313d7eae1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_e2afb752-d4b3-4a9f-b6d1-4274f43d2eb2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IntangibleAssetsNetIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:to="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_e2afb752-d4b3-4a9f-b6d1-4274f43d2eb2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_dbd0b83f-af4e-4433-a28f-df9616664ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4cd98e22-4622-4fd2-b552-4a728fb20a5d" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_dbd0b83f-af4e-4433-a28f-df9616664ab0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_355378e2-9348-45a4-b6ae-5e0cd287bf70" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_dbd0b83f-af4e-4433-a28f-df9616664ab0" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_355378e2-9348-45a4-b6ae-5e0cd287bf70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_355378e2-9348-45a4-b6ae-5e0cd287bf70_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_355378e2-9348-45a4-b6ae-5e0cd287bf70" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_355378e2-9348-45a4-b6ae-5e0cd287bf70_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_d67a507d-3093-483b-9e46-2f0471765a54" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_355378e2-9348-45a4-b6ae-5e0cd287bf70" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_d67a507d-3093-483b-9e46-2f0471765a54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_4a641a8c-a943-40d1-9f35-538ab50e37b8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_d67a507d-3093-483b-9e46-2f0471765a54" xlink:to="loc_us-gaap_TradeNamesMember_4a641a8c-a943-40d1-9f35-538ab50e37b8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/DEBTCreditFacilitiesDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#DEBTCreditFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/DEBTCreditFacilitiesDetails" xlink:type="extended" id="i2382a41289004cdba82fd200b415036e_DEBTCreditFacilitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_bbafb808-4ecc-4ae1-ad14-95d0307c553e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_DebtInstrumentTerm_bbafb808-4ecc-4ae1-ad14-95d0307c553e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_769bd883-bba5-4794-9c3b-8c8affa52d67" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_769bd883-bba5-4794-9c3b-8c8affa52d67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_6646c26c-3d56-4ae5-ab34-4279df0c36fd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_6646c26c-3d56-4ae5-ab34-4279df0c36fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_fb79152d-291a-47e9-bfe3-733a01a7b99c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_fb79152d-291a-47e9-bfe3-733a01a7b99c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DebtInstrumentFinancialCovenantMinimumEBITDAR_744ecbf6-8801-4eec-a390-2ad2bc55d8a2" xlink:href="sncy-20221231.xsd#sncy_DebtInstrumentFinancialCovenantMinimumEBITDAR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_sncy_DebtInstrumentFinancialCovenantMinimumEBITDAR_744ecbf6-8801-4eec-a390-2ad2bc55d8a2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DebtInstrumentFinancialCovenantMinimumLiquidity_e1aaa453-c48d-49c7-bfca-467bb656ac56" xlink:href="sncy-20221231.xsd#sncy_DebtInstrumentFinancialCovenantMinimumLiquidity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_sncy_DebtInstrumentFinancialCovenantMinimumLiquidity_e1aaa453-c48d-49c7-bfca-467bb656ac56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_7fe36302-8788-4beb-bfe5-545bab920c11" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_7fe36302-8788-4beb-bfe5-545bab920c11" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_280eddb2-2cc0-4c8c-a3ae-155b8aa392d0" xlink:href="sncy-20221231.xsd#sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_sncy_NumberOfPurchasedAircraftsPreviouslyUnderOperatingLeases_280eddb2-2cc0-4c8c-a3ae-155b8aa392d0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_e9c746ac-d451-41e3-b7e6-7ca7e02af74a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_LineOfCredit_e9c746ac-d451-41e3-b7e6-7ca7e02af74a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_39b0a3b7-5868-4439-ad28-147be470a25d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_39b0a3b7-5868-4439-ad28-147be470a25d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_LineOfCreditFacilityAmountAvailable_c990e7ea-b8c2-478b-ae23-0e7deede5a82" xlink:href="sncy-20221231.xsd#sncy_LineOfCreditFacilityAmountAvailable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_sncy_LineOfCreditFacilityAmountAvailable_c990e7ea-b8c2-478b-ae23-0e7deede5a82" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_cd3008f3-af83-4c13-8850-b33bb74249f1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_713b45c6-803e-478d-8acb-fce4d753e070" xlink:to="loc_us-gaap_DebtInstrumentTable_cd3008f3-af83-4c13-8850-b33bb74249f1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_5fef5b7a-67ea-455e-be05-0e9c108b8b0e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cd3008f3-af83-4c13-8850-b33bb74249f1" xlink:to="loc_us-gaap_DebtInstrumentAxis_5fef5b7a-67ea-455e-be05-0e9c108b8b0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5fef5b7a-67ea-455e-be05-0e9c108b8b0e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_5fef5b7a-67ea-455e-be05-0e9c108b8b0e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5fef5b7a-67ea-455e-be05-0e9c108b8b0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_472ec581-189f-4bd4-8192-ecd309b0582d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_5fef5b7a-67ea-455e-be05-0e9c108b8b0e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_472ec581-189f-4bd4-8192-ecd309b0582d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PriorRevolvingCreditAgreementMember_7fc3315b-ea85-47f5-bd8f-20f25e74c8a8" xlink:href="sncy-20221231.xsd#sncy_PriorRevolvingCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_472ec581-189f-4bd4-8192-ecd309b0582d" xlink:to="loc_sncy_PriorRevolvingCreditAgreementMember_7fc3315b-ea85-47f5-bd8f-20f25e74c8a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CreditFacilitiesMember_c9286f5d-d9de-463c-af1f-6a404bdceadf" xlink:href="sncy-20221231.xsd#sncy_CreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_472ec581-189f-4bd4-8192-ecd309b0582d" xlink:to="loc_sncy_CreditFacilitiesMember_c9286f5d-d9de-463c-af1f-6a404bdceadf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_049f9134-cb8c-4177-bdea-3210a90bfdb9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_CreditFacilitiesMember_c9286f5d-d9de-463c-af1f-6a404bdceadf" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_049f9134-cb8c-4177-bdea-3210a90bfdb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DelayedDrawTermLoanFacilityMember_c48bb5af-515e-4576-b4d4-c1543d0a20e1" xlink:href="sncy-20221231.xsd#sncy_DelayedDrawTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_CreditFacilitiesMember_c9286f5d-d9de-463c-af1f-6a404bdceadf" xlink:to="loc_sncy_DelayedDrawTermLoanFacilityMember_c48bb5af-515e-4576-b4d4-c1543d0a20e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_3f236cc8-7cb7-4364-bc85-e41219ec18e9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cd3008f3-af83-4c13-8850-b33bb74249f1" xlink:to="loc_us-gaap_VariableRateAxis_3f236cc8-7cb7-4364-bc85-e41219ec18e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_3f236cc8-7cb7-4364-bc85-e41219ec18e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_3f236cc8-7cb7-4364-bc85-e41219ec18e9" xlink:to="loc_us-gaap_VariableRateDomain_3f236cc8-7cb7-4364-bc85-e41219ec18e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_d4d4bf6d-cd29-4062-9712-dfc72642dc7d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_3f236cc8-7cb7-4364-bc85-e41219ec18e9" xlink:to="loc_us-gaap_VariableRateDomain_d4d4bf6d-cd29-4062-9712-dfc72642dc7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_024a44bd-121a-4de8-a90c-874c2ab7d915" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d4d4bf6d-cd29-4062-9712-dfc72642dc7d" xlink:to="loc_us-gaap_BaseRateMember_024a44bd-121a-4de8-a90c-874c2ab7d915" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a76456b3-b70e-4775-bdf3-621e9bd613eb" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cd3008f3-af83-4c13-8850-b33bb74249f1" xlink:to="loc_srt_RangeAxis_a76456b3-b70e-4775-bdf3-621e9bd613eb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a76456b3-b70e-4775-bdf3-621e9bd613eb_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a76456b3-b70e-4775-bdf3-621e9bd613eb" xlink:to="loc_srt_RangeMember_a76456b3-b70e-4775-bdf3-621e9bd613eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_34c71a54-64e4-40a2-8943-e720e7df2248" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a76456b3-b70e-4775-bdf3-621e9bd613eb" xlink:to="loc_srt_RangeMember_34c71a54-64e4-40a2-8943-e720e7df2248" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_38ac677b-00b6-4939-8125-786813987eab" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_34c71a54-64e4-40a2-8943-e720e7df2248" xlink:to="loc_srt_MinimumMember_38ac677b-00b6-4939-8125-786813987eab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_92be89aa-fdfa-4348-ad2e-7c78ee0a6af2" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_34c71a54-64e4-40a2-8943-e720e7df2248" xlink:to="loc_srt_MaximumMember_92be89aa-fdfa-4348-ad2e-7c78ee0a6af2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_da403142-ab3f-4852-a786-262cc5154497" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cd3008f3-af83-4c13-8850-b33bb74249f1" xlink:to="loc_us-gaap_CreditFacilityAxis_da403142-ab3f-4852-a786-262cc5154497" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_da403142-ab3f-4852-a786-262cc5154497_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_da403142-ab3f-4852-a786-262cc5154497" xlink:to="loc_us-gaap_CreditFacilityDomain_da403142-ab3f-4852-a786-262cc5154497_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_40d2fe79-fc8e-4b15-9697-911e5f49c0df" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_da403142-ab3f-4852-a786-262cc5154497" xlink:to="loc_us-gaap_CreditFacilityDomain_40d2fe79-fc8e-4b15-9697-911e5f49c0df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_c3b6b077-6a12-444d-93c3-28e1d24f78f0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_40d2fe79-fc8e-4b15-9697-911e5f49c0df" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_c3b6b077-6a12-444d-93c3-28e1d24f78f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_071b8631-337f-44fe-a745-e38a91c4e9bb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cd3008f3-af83-4c13-8850-b33bb74249f1" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_071b8631-337f-44fe-a745-e38a91c4e9bb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_071b8631-337f-44fe-a745-e38a91c4e9bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_071b8631-337f-44fe-a745-e38a91c4e9bb" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_071b8631-337f-44fe-a745-e38a91c4e9bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5c357c64-8fa7-4734-8510-3f5ddc19f064" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_071b8631-337f-44fe-a745-e38a91c4e9bb" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5c357c64-8fa7-4734-8510-3f5ddc19f064" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_9238d410-b05a-43a8-87a9-321ece5f5a01" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5c357c64-8fa7-4734-8510-3f5ddc19f064" xlink:to="loc_us-gaap_LineOfCreditMember_9238d410-b05a-43a8-87a9-321ece5f5a01" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/DEBTLongtermDebtDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#DEBTLongtermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/DEBTLongtermDebtDetails" xlink:type="extended" id="icee5678be3f94227803e237c55b800d2_DEBTLongtermDebtDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_025d3fb2-ff7d-43ac-9968-d849db7b4d58" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_025d3fb2-ff7d-43ac-9968-d849db7b4d58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftFinancedByDebtIssuance_515455f9-ed18-464b-8ad8-6ac4afb9c356" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftFinancedByDebtIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_sncy_NumberOfAircraftFinancedByDebtIssuance_515455f9-ed18-464b-8ad8-6ac4afb9c356" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_06de3a6e-d919-48b9-aac4-fbe443e638f5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_06de3a6e-d919-48b9-aac4-fbe443e638f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftOwnedAndRefinanced_4689f559-dc4e-4aca-92d3-201808f38cff" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftOwnedAndRefinanced"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_sncy_NumberOfAircraftOwnedAndRefinanced_4689f559-dc4e-4aca-92d3-201808f38cff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftOwned_3f1231a4-10b9-4256-a2b8-1d2a73da7fd1" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftOwned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_sncy_NumberOfAircraftOwned_3f1231a4-10b9-4256-a2b8-1d2a73da7fd1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftAcquiredInCurrentPeriod_6e18cc96-a3c9-44d2-b8b2-e316ffdab01a" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftAcquiredInCurrentPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_sncy_NumberOfAircraftAcquiredInCurrentPeriod_6e18cc96-a3c9-44d2-b8b2-e316ffdab01a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftBoughtOutFromAnExistingFinanceLease_f729b374-4c3f-4c24-b153-a2a838878698" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftBoughtOutFromAnExistingFinanceLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_sncy_NumberOfAircraftBoughtOutFromAnExistingFinanceLease_f729b374-4c3f-4c24-b153-a2a838878698" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestCostsCapitalized_4a0a2922-c07b-42ff-8f1c-fa0bb3d97835" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestCostsCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_us-gaap_InterestCostsCapitalized_4a0a2922-c07b-42ff-8f1c-fa0bb3d97835" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfUsedAircraftsPurchasedOrRefinanced_53c66af6-b94c-4592-b8aa-ca79cd341a4b" xlink:href="sncy-20221231.xsd#sncy_NumberOfUsedAircraftsPurchasedOrRefinanced"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_sncy_NumberOfUsedAircraftsPurchasedOrRefinanced_53c66af6-b94c-4592-b8aa-ca79cd341a4b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_b26d16a6-c7d2-497d-8b96-e8e07aab898f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b090d005-4267-4149-b501-dbc5e17a41da" xlink:to="loc_us-gaap_DebtInstrumentTable_b26d16a6-c7d2-497d-8b96-e8e07aab898f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_f42fa0b7-bd05-45f3-b64c-d94d94f54b99" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b26d16a6-c7d2-497d-8b96-e8e07aab898f" xlink:to="loc_us-gaap_DebtInstrumentAxis_f42fa0b7-bd05-45f3-b64c-d94d94f54b99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_f42fa0b7-bd05-45f3-b64c-d94d94f54b99_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_f42fa0b7-bd05-45f3-b64c-d94d94f54b99" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_f42fa0b7-bd05-45f3-b64c-d94d94f54b99_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_f29ad711-cb3c-41cb-b888-f2a78965ca11" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_f42fa0b7-bd05-45f3-b64c-d94d94f54b99" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_f29ad711-cb3c-41cb-b888-f2a78965ca11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NotesPayableUnderCompanyS20191EETCAgreementMember_8ef23f35-818d-4a41-8463-026a69a863b6" xlink:href="sncy-20221231.xsd#sncy_NotesPayableUnderCompanyS20191EETCAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f29ad711-cb3c-41cb-b888-f2a78965ca11" xlink:to="loc_sncy_NotesPayableUnderCompanyS20191EETCAgreementMember_8ef23f35-818d-4a41-8463-026a69a863b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CreditFacilitiesMember_5c432288-5c51-4e1f-9b1a-c4fb6c52e6f8" xlink:href="sncy-20221231.xsd#sncy_CreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f29ad711-cb3c-41cb-b888-f2a78965ca11" xlink:to="loc_sncy_CreditFacilitiesMember_5c432288-5c51-4e1f-9b1a-c4fb6c52e6f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DelayedDrawTermLoanFacilityMember_d5ca3a40-d94f-4a4c-b66e-7ad11ac25afb" xlink:href="sncy-20221231.xsd#sncy_DelayedDrawTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_CreditFacilitiesMember_5c432288-5c51-4e1f-9b1a-c4fb6c52e6f8" xlink:to="loc_sncy_DelayedDrawTermLoanFacilityMember_d5ca3a40-d94f-4a4c-b66e-7ad11ac25afb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_A20221EETCAgreementNotesPayableMember_64e55891-3de5-4c4d-9899-20417189527a" xlink:href="sncy-20221231.xsd#sncy_A20221EETCAgreementNotesPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f29ad711-cb3c-41cb-b888-f2a78965ca11" xlink:to="loc_sncy_A20221EETCAgreementNotesPayableMember_64e55891-3de5-4c4d-9899-20417189527a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_0ab757e4-3853-4d63-a446-c53ab86c18bc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f29ad711-cb3c-41cb-b888-f2a78965ca11" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_0ab757e4-3853-4d63-a446-c53ab86c18bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6f9e257e-1b23-411f-958f-a54d65a2f6f2" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b26d16a6-c7d2-497d-8b96-e8e07aab898f" xlink:to="loc_srt_RangeAxis_6f9e257e-1b23-411f-958f-a54d65a2f6f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6f9e257e-1b23-411f-958f-a54d65a2f6f2_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6f9e257e-1b23-411f-958f-a54d65a2f6f2" xlink:to="loc_srt_RangeMember_6f9e257e-1b23-411f-958f-a54d65a2f6f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_8f1ea12e-c650-43da-ae75-ce8aa8b12fc1" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6f9e257e-1b23-411f-958f-a54d65a2f6f2" xlink:to="loc_srt_RangeMember_8f1ea12e-c650-43da-ae75-ce8aa8b12fc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5c436677-5884-436c-b883-02de8705652c" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8f1ea12e-c650-43da-ae75-ce8aa8b12fc1" xlink:to="loc_srt_MinimumMember_5c436677-5884-436c-b883-02de8705652c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_70792601-b88f-4209-aefa-04cd2ffe7015" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8f1ea12e-c650-43da-ae75-ce8aa8b12fc1" xlink:to="loc_srt_MaximumMember_70792601-b88f-4209-aefa-04cd2ffe7015" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_396f6649-b5fe-4e94-9d50-6ac68b1186b8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b26d16a6-c7d2-497d-8b96-e8e07aab898f" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_396f6649-b5fe-4e94-9d50-6ac68b1186b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_396f6649-b5fe-4e94-9d50-6ac68b1186b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_396f6649-b5fe-4e94-9d50-6ac68b1186b8" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_396f6649-b5fe-4e94-9d50-6ac68b1186b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_77854643-a465-41db-a623-f82668462437" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_396f6649-b5fe-4e94-9d50-6ac68b1186b8" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_77854643-a465-41db-a623-f82668462437" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_184702f1-5091-45c0-a5d0-5f471538af9c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_77854643-a465-41db-a623-f82668462437" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_184702f1-5091-45c0-a5d0-5f471538af9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_b01240f9-fd11-40e0-a455-e7e27bbd184f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_77854643-a465-41db-a623-f82668462437" xlink:to="loc_us-gaap_LineOfCreditMember_b01240f9-fd11-40e0-a455-e7e27bbd184f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/DEBTLongtermDebtscheduleDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#DEBTLongtermDebtscheduleDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/DEBTLongtermDebtscheduleDetails" xlink:type="extended" id="icae810a0f95b492ba252acdcc9ddba2e_DEBTLongtermDebtscheduleDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_dd3247f9-7e06-4a60-a9a5-68c6137e4a3f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_dd3247f9-7e06-4a60-a9a5-68c6137e4a3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_5e438b0d-7c4f-48f0-a96b-e5059d102b45" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_5e438b0d-7c4f-48f0-a96b-e5059d102b45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_94833aaf-c9b0-49c0-b810-94dd60c5ea96" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_LongTermDebtCurrent_94833aaf-c9b0-49c0-b810-94dd60c5ea96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_04613501-259c-4baa-8f11-e8662053f92a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_04613501-259c-4baa-8f11-e8662053f92a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_5bbc9b83-9eb4-4531-9e6a-ab55e90443a6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_5bbc9b83-9eb4-4531-9e6a-ab55e90443a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0a317eea-197a-4bc7-8c17-42416405ffbc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0a317eea-197a-4bc7-8c17-42416405ffbc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_a33bba61-3b47-4d99-8228-8013a59d00c6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_a33bba61-3b47-4d99-8228-8013a59d00c6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_cc29f227-6212-4060-bece-3e8cccfa5fca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d14f92b8-9135-4c8a-8e9b-d9f85918ead2" xlink:to="loc_us-gaap_DebtInstrumentTable_cc29f227-6212-4060-bece-3e8cccfa5fca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_41a6ee58-4ad7-451a-bc46-62d37e99197f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cc29f227-6212-4060-bece-3e8cccfa5fca" xlink:to="loc_us-gaap_DebtInstrumentAxis_41a6ee58-4ad7-451a-bc46-62d37e99197f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_41a6ee58-4ad7-451a-bc46-62d37e99197f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_41a6ee58-4ad7-451a-bc46-62d37e99197f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_41a6ee58-4ad7-451a-bc46-62d37e99197f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_106276f0-3539-4595-934c-2b430b614bd2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_41a6ee58-4ad7-451a-bc46-62d37e99197f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_106276f0-3539-4595-934c-2b430b614bd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NotesPayableUnderCompanyS20191EETCAgreementMember_2e11d9d5-e59a-4dae-bfc3-84093fec7022" xlink:href="sncy-20221231.xsd#sncy_NotesPayableUnderCompanyS20191EETCAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_106276f0-3539-4595-934c-2b430b614bd2" xlink:to="loc_sncy_NotesPayableUnderCompanyS20191EETCAgreementMember_2e11d9d5-e59a-4dae-bfc3-84093fec7022" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_A20221EETCAgreementNotesPayableMember_616ee852-9955-4f62-beb3-55d77d34cd3a" xlink:href="sncy-20221231.xsd#sncy_A20221EETCAgreementNotesPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_106276f0-3539-4595-934c-2b430b614bd2" xlink:to="loc_sncy_A20221EETCAgreementNotesPayableMember_616ee852-9955-4f62-beb3-55d77d34cd3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DelayedDrawTermLoanFacilityMember_fe78cc85-f639-48e3-a178-196a2039459c" xlink:href="sncy-20221231.xsd#sncy_DelayedDrawTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_106276f0-3539-4595-934c-2b430b614bd2" xlink:to="loc_sncy_DelayedDrawTermLoanFacilityMember_fe78cc85-f639-48e3-a178-196a2039459c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_5501bb8a-ff3f-44f8-9722-36a00b0be8e2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_106276f0-3539-4595-934c-2b430b614bd2" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_5501bb8a-ff3f-44f8-9722-36a00b0be8e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_b2ba6a21-bf5c-405f-ba79-2fc7255382e9" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cc29f227-6212-4060-bece-3e8cccfa5fca" xlink:to="loc_srt_RangeAxis_b2ba6a21-bf5c-405f-ba79-2fc7255382e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b2ba6a21-bf5c-405f-ba79-2fc7255382e9_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_b2ba6a21-bf5c-405f-ba79-2fc7255382e9" xlink:to="loc_srt_RangeMember_b2ba6a21-bf5c-405f-ba79-2fc7255382e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_773efda2-6cd0-43eb-b848-8f377449e296" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_b2ba6a21-bf5c-405f-ba79-2fc7255382e9" xlink:to="loc_srt_RangeMember_773efda2-6cd0-43eb-b848-8f377449e296" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_35082490-42f1-42d9-889f-3586ccc35e46" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_773efda2-6cd0-43eb-b848-8f377449e296" xlink:to="loc_srt_MinimumMember_35082490-42f1-42d9-889f-3586ccc35e46" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_553fecb6-3ccf-453c-ad22-125b25a1abd3" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_773efda2-6cd0-43eb-b848-8f377449e296" xlink:to="loc_srt_MaximumMember_553fecb6-3ccf-453c-ad22-125b25a1abd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_b520e658-36d9-435c-af87-e9d75a12c111" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_cc29f227-6212-4060-bece-3e8cccfa5fca" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_b520e658-36d9-435c-af87-e9d75a12c111" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_b520e658-36d9-435c-af87-e9d75a12c111_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_b520e658-36d9-435c-af87-e9d75a12c111" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_b520e658-36d9-435c-af87-e9d75a12c111_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d34f05de-34cf-4986-bb91-2c8df9d89cd6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_b520e658-36d9-435c-af87-e9d75a12c111" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d34f05de-34cf-4986-bb91-2c8df9d89cd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_eec7d4a1-9ce7-47e6-ad60-de6c8fa4a306" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d34f05de-34cf-4986-bb91-2c8df9d89cd6" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_eec7d4a1-9ce7-47e6-ad60-de6c8fa4a306" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/LEASESSummaryDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#LEASESSummaryDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/LEASESSummaryDetails" xlink:type="extended" id="ic179f2e0c9384c34a95b779aaf95f14e_LEASESSummaryDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfCategoriesInOperatingLeases_98998b1b-6654-45a6-94d7-b840f8d0f3cf" xlink:href="sncy-20221231.xsd#sncy_NumberOfCategoriesInOperatingLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_sncy_NumberOfCategoriesInOperatingLeases_98998b1b-6654-45a6-94d7-b840f8d0f3cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfLeasesForAircraft_bcecda29-a56d-4087-bd5c-b636a67bec27" xlink:href="sncy-20221231.xsd#sncy_NumberOfLeasesForAircraft"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_sncy_NumberOfLeasesForAircraft_bcecda29-a56d-4087-bd5c-b636a67bec27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfLeasesUnderFinanceLeases_038fb992-b4b0-49ac-a5c7-9e9338eccd49" xlink:href="sncy-20221231.xsd#sncy_NumberOfLeasesUnderFinanceLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_sncy_NumberOfLeasesUnderFinanceLeases_038fb992-b4b0-49ac-a5c7-9e9338eccd49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfLeasesUnderRightOfUseOperatingLeases_a076a1be-965b-4521-858f-59d6bb037563" xlink:href="sncy-20221231.xsd#sncy_NumberOfLeasesUnderRightOfUseOperatingLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_sncy_NumberOfLeasesUnderRightOfUseOperatingLeases_a076a1be-965b-4521-858f-59d6bb037563" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_aed41dd1-1feb-4e5d-9407-5d701330abbc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_aed41dd1-1feb-4e5d-9407-5d701330abbc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfFreightersSubleasedDirectly_7d45ffc2-3982-470d-ab09-69c55a770c4e" xlink:href="sncy-20221231.xsd#sncy_NumberOfFreightersSubleasedDirectly"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_sncy_NumberOfFreightersSubleasedDirectly_7d45ffc2-3982-470d-ab09-69c55a770c4e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_d37602f7-fa47-4c37-9029-2164e1ab0d6d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_d37602f7-fa47-4c37-9029-2164e1ab0d6d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_32507720-e638-4461-9287-71da67524fe4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_us-gaap_OperatingLeaseLiability_32507720-e638-4461-9287-71da67524fe4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_ec5d2fc2-75a9-45b1-b54d-f856d9bb0ce2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_496a6088-03eb-4391-a5e6-8413facb811c" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_ec5d2fc2-75a9-45b1-b54d-f856d9bb0ce2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caf88b36-ecec-46ac-969c-783d5d373eba" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_ec5d2fc2-75a9-45b1-b54d-f856d9bb0ce2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caf88b36-ecec-46ac-969c-783d5d373eba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_caf88b36-ecec-46ac-969c-783d5d373eba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caf88b36-ecec-46ac-969c-783d5d373eba" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_caf88b36-ecec-46ac-969c-783d5d373eba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c0c34c7f-5e33-4219-aba8-94d2446e1d20" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_caf88b36-ecec-46ac-969c-783d5d373eba" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c0c34c7f-5e33-4219-aba8-94d2446e1d20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftMember_495919c3-ac98-403f-a744-4794df6d00b8" xlink:href="sncy-20221231.xsd#sncy_AircraftMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c0c34c7f-5e33-4219-aba8-94d2446e1d20" xlink:to="loc_sncy_AircraftMember_495919c3-ac98-403f-a744-4794df6d00b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateMember_6e063e71-0ce4-4c3d-af5b-8d6fa724be4b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c0c34c7f-5e33-4219-aba8-94d2446e1d20" xlink:to="loc_us-gaap_RealEstateMember_6e063e71-0ce4-4c3d-af5b-8d6fa724be4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftsOperatedForAmazonMember_be867504-3f97-44f8-ae00-fb1aa39d3096" xlink:href="sncy-20221231.xsd#sncy_AircraftsOperatedForAmazonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c0c34c7f-5e33-4219-aba8-94d2446e1d20" xlink:to="loc_sncy_AircraftsOperatedForAmazonMember_be867504-3f97-44f8-ae00-fb1aa39d3096" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6e4bcaeb-1b7a-43fe-a03b-41d7dc7b42d7" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_ec5d2fc2-75a9-45b1-b54d-f856d9bb0ce2" xlink:to="loc_srt_RangeAxis_6e4bcaeb-1b7a-43fe-a03b-41d7dc7b42d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6e4bcaeb-1b7a-43fe-a03b-41d7dc7b42d7_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6e4bcaeb-1b7a-43fe-a03b-41d7dc7b42d7" xlink:to="loc_srt_RangeMember_6e4bcaeb-1b7a-43fe-a03b-41d7dc7b42d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_147a7a34-8e79-4ea6-aaa6-1d34dad4fa02" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6e4bcaeb-1b7a-43fe-a03b-41d7dc7b42d7" xlink:to="loc_srt_RangeMember_147a7a34-8e79-4ea6-aaa6-1d34dad4fa02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_3519d928-e3aa-4e2d-8d2b-05d786446bf8" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_147a7a34-8e79-4ea6-aaa6-1d34dad4fa02" xlink:to="loc_srt_MaximumMember_3519d928-e3aa-4e2d-8d2b-05d786446bf8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/LEASESFinanceleaseobligationsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#LEASESFinanceleaseobligationsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/LEASESFinanceleaseobligationsDetails" xlink:type="extended" id="i28e47634e9f44b7fa75722f32da4b2eb_LEASESFinanceleaseobligationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_39c4a33e-41d6-4c27-a0ed-6eb8cbf01daa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_39c4a33e-41d6-4c27-a0ed-6eb8cbf01daa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_4ba4cbdc-8c7e-4a6d-95db-406f9425f6d3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_4ba4cbdc-8c7e-4a6d-95db-406f9425f6d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_a185ddd6-aea7-4415-a792-b3863dfd77e9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_a185ddd6-aea7-4415-a792-b3863dfd77e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_b83a65d2-120d-4976-b1cb-be267c4e64cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_b83a65d2-120d-4976-b1cb-be267c4e64cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_9f0986ae-5ccc-4e86-9935-90c54490df9c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_9f0986ae-5ccc-4e86-9935-90c54490df9c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_c519dca2-2ce8-49b7-9a77-0bd4d99d9707" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_c519dca2-2ce8-49b7-9a77-0bd4d99d9707" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_4d36f492-8f57-42b5-bb1f-d6b5dc85d721" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_4d36f492-8f57-42b5-bb1f-d6b5dc85d721" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_4f024c7a-d95f-4173-9309-732ed25aabce" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_4f024c7a-d95f-4173-9309-732ed25aabce" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_7cb83746-b36c-40fa-8270-82e9c386fec1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiability_7cb83746-b36c-40fa-8270-82e9c386fec1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_5a57f6bf-0955-444f-9986-afa0b0b0b1cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_5a57f6bf-0955-444f-9986-afa0b0b0b1cf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_d05421dc-7cbc-4859-90ba-b422d566abef" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_d05421dc-7cbc-4859-90ba-b422d566abef" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_5dc89156-f8f0-4450-a9ee-4052d05b9f58" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6510581d-2d7f-43a0-a990-dd6faccee953" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_5dc89156-f8f0-4450-a9ee-4052d05b9f58" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_35f72c81-3224-400a-98b4-e2057b3c71fe" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_5dc89156-f8f0-4450-a9ee-4052d05b9f58" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_35f72c81-3224-400a-98b4-e2057b3c71fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_35f72c81-3224-400a-98b4-e2057b3c71fe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_35f72c81-3224-400a-98b4-e2057b3c71fe" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_35f72c81-3224-400a-98b4-e2057b3c71fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_879629b7-0eb5-41d7-849f-aeed5917b472" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_35f72c81-3224-400a-98b4-e2057b3c71fe" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_879629b7-0eb5-41d7-849f-aeed5917b472" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftMember_f399c2b9-8cbb-48b6-a6b3-3e83d8373d53" xlink:href="sncy-20221231.xsd#sncy_AircraftMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_879629b7-0eb5-41d7-849f-aeed5917b472" xlink:to="loc_sncy_AircraftMember_f399c2b9-8cbb-48b6-a6b3-3e83d8373d53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateMember_cd452240-89a7-4c4c-9f83-54c9a822261d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_879629b7-0eb5-41d7-849f-aeed5917b472" xlink:to="loc_us-gaap_RealEstateMember_cd452240-89a7-4c4c-9f83-54c9a822261d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/LEASESOperatingleaseobligationsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#LEASESOperatingleaseobligationsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/LEASESOperatingleaseobligationsDetails" xlink:type="extended" id="i9b12895afabf4514825fb95d9ebb2ac4_LEASESOperatingleaseobligationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_a74764d8-be9c-497e-9190-370291e9e264" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_a74764d8-be9c-497e-9190-370291e9e264" xlink:to="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_5ce344c1-8dd5-436d-80e1-ef862b21ed4a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_5ce344c1-8dd5-436d-80e1-ef862b21ed4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_9c3aebc7-a879-4e27-a4f8-7ba72e5179b7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_9c3aebc7-a879-4e27-a4f8-7ba72e5179b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_858129e2-9228-4265-825d-5ee0678e09dd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_858129e2-9228-4265-825d-5ee0678e09dd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_1b2a7cd0-ae95-40f1-9c7f-88b5107bd2c3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_1b2a7cd0-ae95-40f1-9c7f-88b5107bd2c3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_35b3592c-2e2c-4404-a8fd-f4fd3f9b0077" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_35b3592c-2e2c-4404-a8fd-f4fd3f9b0077" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_56f69236-28b3-4c2f-a999-322b2c9fef31" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_56f69236-28b3-4c2f-a999-322b2c9fef31" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_d3717e27-3208-4145-bd5e-744e26dcbd9d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_d3717e27-3208-4145-bd5e-744e26dcbd9d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_e1d774fa-7ad0-4e03-9ef3-8d7d79e2f4a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_e1d774fa-7ad0-4e03-9ef3-8d7d79e2f4a3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_689e5ab6-fd5d-42b7-9e2c-5d7d93d7d421" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_OperatingLeaseLiability_689e5ab6-fd5d-42b7-9e2c-5d7d93d7d421" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_dc2e860f-34fb-433b-b044-bdb2b4f127ee" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_dc2e860f-34fb-433b-b044-bdb2b4f127ee" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_816981a3-8eea-497e-a0d8-ade738ebbdcf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_8b2acb3e-69f0-45c9-9319-b2bc5793be2e" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_816981a3-8eea-497e-a0d8-ade738ebbdcf" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_6ce487c3-b318-4fae-a500-ba90e6a5089e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_a74764d8-be9c-497e-9190-370291e9e264" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_6ce487c3-b318-4fae-a500-ba90e6a5089e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_87be444f-ae21-4c83-adaf-b41faa4b3a9a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_6ce487c3-b318-4fae-a500-ba90e6a5089e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_87be444f-ae21-4c83-adaf-b41faa4b3a9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_87be444f-ae21-4c83-adaf-b41faa4b3a9a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_87be444f-ae21-4c83-adaf-b41faa4b3a9a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_87be444f-ae21-4c83-adaf-b41faa4b3a9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_10548038-1a98-432d-ae5b-74e7df7d8c00" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_87be444f-ae21-4c83-adaf-b41faa4b3a9a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_10548038-1a98-432d-ae5b-74e7df7d8c00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftMember_3c9e766d-dfc0-454b-a48b-7a728f4448a4" xlink:href="sncy-20221231.xsd#sncy_AircraftMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_10548038-1a98-432d-ae5b-74e7df7d8c00" xlink:to="loc_sncy_AircraftMember_3c9e766d-dfc0-454b-a48b-7a728f4448a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateMember_75bbf040-7c98-4efa-8e28-1f538912436a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_10548038-1a98-432d-ae5b-74e7df7d8c00" xlink:to="loc_us-gaap_RealEstateMember_75bbf040-7c98-4efa-8e28-1f538912436a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/LEASESLeasecostDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#LEASESLeasecostDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/LEASESLeasecostDetails" xlink:type="extended" id="if1104dd057a847a6a52bfb00359b986a_LEASESLeasecostDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_0e13ab67-9b2f-4a08-912d-f1be0a96f983" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCostAbstract_68b281df-4981-4fdb-beec-2b43590c2914" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LeaseCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0e13ab67-9b2f-4a08-912d-f1be0a96f983" xlink:to="loc_us-gaap_LeaseCostAbstract_68b281df-4981-4fdb-beec-2b43590c2914" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_FinanceLeasesCostAbstract_f4cc5451-9049-4b31-8e5a-6210483d236b" xlink:href="sncy-20221231.xsd#sncy_FinanceLeasesCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseCostAbstract_68b281df-4981-4fdb-beec-2b43590c2914" xlink:to="loc_sncy_FinanceLeasesCostAbstract_f4cc5451-9049-4b31-8e5a-6210483d236b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_f3513243-4971-4735-b7e9-555f3a137db5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_FinanceLeasesCostAbstract_f4cc5451-9049-4b31-8e5a-6210483d236b" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_f3513243-4971-4735-b7e9-555f3a137db5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_56e32175-b257-4b0e-813c-e4c80a5959c6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_FinanceLeasesCostAbstract_f4cc5451-9049-4b31-8e5a-6210483d236b" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_56e32175-b257-4b0e-813c-e4c80a5959c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OperatingLeasesCostAbstract_f6e93a00-4d91-4c84-914d-9f9ecb159236" xlink:href="sncy-20221231.xsd#sncy_OperatingLeasesCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseCostAbstract_68b281df-4981-4fdb-beec-2b43590c2914" xlink:to="loc_sncy_OperatingLeasesCostAbstract_f6e93a00-4d91-4c84-914d-9f9ecb159236" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_9f866886-f86c-4b05-ae7e-37a96c84beca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_OperatingLeasesCostAbstract_f6e93a00-4d91-4c84-914d-9f9ecb159236" xlink:to="loc_us-gaap_OperatingLeaseCost_9f866886-f86c-4b05-ae7e-37a96c84beca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_057b400d-609d-4f41-a1e5-e8a8ddf9c564" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_OperatingLeasesCostAbstract_f6e93a00-4d91-4c84-914d-9f9ecb159236" xlink:to="loc_us-gaap_ShortTermLeaseCost_057b400d-609d-4f41-a1e5-e8a8ddf9c564" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseIncome_87f95c93-1701-413d-9807-0a23e48c9b32" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableLeaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_OperatingLeasesCostAbstract_f6e93a00-4d91-4c84-914d-9f9ecb159236" xlink:to="loc_us-gaap_VariableLeaseIncome_87f95c93-1701-413d-9807-0a23e48c9b32" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_50ccf6f0-0d4c-4e97-8177-a3fb1c3824e1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_OperatingLeasesCostAbstract_f6e93a00-4d91-4c84-914d-9f9ecb159236" xlink:to="loc_us-gaap_VariableLeaseCost_50ccf6f0-0d4c-4e97-8177-a3fb1c3824e1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_81498a33-4b2d-46c3-abd8-ba3c13937ec5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_OperatingLeasesCostAbstract_f6e93a00-4d91-4c84-914d-9f9ecb159236" xlink:to="loc_us-gaap_LeaseCost_81498a33-4b2d-46c3-abd8-ba3c13937ec5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AmortizationOfOverMarketLiabilities_8b2535bf-a6a0-4bd2-9ffb-1e3107677611" xlink:href="sncy-20221231.xsd#sncy_AmortizationOfOverMarketLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseCostAbstract_68b281df-4981-4fdb-beec-2b43590c2914" xlink:to="loc_sncy_AmortizationOfOverMarketLiabilities_8b2535bf-a6a0-4bd2-9ffb-1e3107677611" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_949000a7-8057-4b5b-9ab2-977194247717" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_0e13ab67-9b2f-4a08-912d-f1be0a96f983" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_949000a7-8057-4b5b-9ab2-977194247717" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c1fca426-77bb-4823-89a3-c8bc66c8a082" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_949000a7-8057-4b5b-9ab2-977194247717" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c1fca426-77bb-4823-89a3-c8bc66c8a082" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c1fca426-77bb-4823-89a3-c8bc66c8a082_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c1fca426-77bb-4823-89a3-c8bc66c8a082" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c1fca426-77bb-4823-89a3-c8bc66c8a082_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4329a675-a0eb-4785-be82-d2d16ab39149" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c1fca426-77bb-4823-89a3-c8bc66c8a082" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4329a675-a0eb-4785-be82-d2d16ab39149" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_AircraftMember_98f84b8c-deeb-48d2-bc71-34b54b643082" xlink:href="sncy-20221231.xsd#sncy_AircraftMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4329a675-a0eb-4785-be82-d2d16ab39149" xlink:to="loc_sncy_AircraftMember_98f84b8c-deeb-48d2-bc71-34b54b643082" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OtherMember_c2afb865-a0fd-458a-9d8c-add87b6998ff" xlink:href="sncy-20221231.xsd#sncy_OtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4329a675-a0eb-4785-be82-d2d16ab39149" xlink:to="loc_sncy_OtherMember_c2afb865-a0fd-458a-9d8c-add87b6998ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_be3c16ab-edbb-4099-90a1-cb62dab1ab01" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_949000a7-8057-4b5b-9ab2-977194247717" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_be3c16ab-edbb-4099-90a1-cb62dab1ab01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_be3c16ab-edbb-4099-90a1-cb62dab1ab01_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_be3c16ab-edbb-4099-90a1-cb62dab1ab01" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_be3c16ab-edbb-4099-90a1-cb62dab1ab01_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_d803a190-dd62-49f1-a522-82d1daa9d15a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_be3c16ab-edbb-4099-90a1-cb62dab1ab01" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_d803a190-dd62-49f1-a522-82d1daa9d15a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OverMarketLeaseRatesContraAssetsIncludedInOperatingLeaseRightOfUseAssetsMember_c6501e87-d1f6-49ba-8d4c-1b10d50591e1" xlink:href="sncy-20221231.xsd#sncy_OverMarketLeaseRatesContraAssetsIncludedInOperatingLeaseRightOfUseAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_d803a190-dd62-49f1-a522-82d1daa9d15a" xlink:to="loc_sncy_OverMarketLeaseRatesContraAssetsIncludedInOperatingLeaseRightOfUseAssetsMember_c6501e87-d1f6-49ba-8d4c-1b10d50591e1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/STOCKBASEDCOMPENSATIONAdditionalInformationDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#STOCKBASEDCOMPENSATIONAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/STOCKBASEDCOMPENSATIONAdditionalInformationDetails" xlink:type="extended" id="i4b1bb5314ff54e14b4e7022e10ec1052_STOCKBASEDCOMPENSATIONAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7505a315-be15-47b6-be60-b53aa7e0eacb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7505a315-be15-47b6-be60-b53aa7e0eacb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_fcca1219-df86-4e57-be95-35a0ea007b2b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_fcca1219-df86-4e57-be95-35a0ea007b2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_002bcd15-395c-4d21-96cf-a04474542695" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_002bcd15-395c-4d21-96cf-a04474542695" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_a85f6df1-0081-425f-9909-a5e5016d4f4f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_a85f6df1-0081-425f-9909-a5e5016d4f4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1c16d396-0078-457f-835f-a764756b691b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1c16d396-0078-457f-835f-a764756b691b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6df1852b-0d72-4b13-84db-d001bc1de8bf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6df1852b-0d72-4b13-84db-d001bc1de8bf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_2af971e9-55ef-41eb-9462-84578d5774ac" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_2af971e9-55ef-41eb-9462-84578d5774ac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_abb2c1dd-4348-45df-a95c-4186a280e0f5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_abb2c1dd-4348-45df-a95c-4186a280e0f5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsPercentageVestingEachYearOverFourYearPeriod_bedeb518-8597-42e4-bff2-c0c62c020228" xlink:href="sncy-20221231.xsd#sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsPercentageVestingEachYearOverFourYearPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsPercentageVestingEachYearOverFourYearPeriod_bedeb518-8597-42e4-bff2-c0c62c020228" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardInitialVestingPeriodFromGrantDate_fc3d77c0-d262-49ff-a259-46f7f904355f" xlink:href="sncy-20221231.xsd#sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardInitialVestingPeriodFromGrantDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardInitialVestingPeriodFromGrantDate_fc3d77c0-d262-49ff-a259-46f7f904355f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_13e2d45f-ec7c-4c4f-b049-339d343c5ec3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_13e2d45f-ec7c-4c4f-b049-339d343c5ec3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_c0ea6dba-8f24-42e7-aeec-4b781a334d1f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_c0ea6dba-8f24-42e7-aeec-4b781a334d1f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3e0cf93-5a53-46e5-94da-5afa85e024d4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bc292eec-21d9-4185-a641-f51f96ead098" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3e0cf93-5a53-46e5-94da-5afa85e024d4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_5047fe3a-feaa-4f45-b7e1-e6ae86154f0e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3e0cf93-5a53-46e5-94da-5afa85e024d4" xlink:to="loc_us-gaap_PlanNameAxis_5047fe3a-feaa-4f45-b7e1-e6ae86154f0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_5047fe3a-feaa-4f45-b7e1-e6ae86154f0e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_5047fe3a-feaa-4f45-b7e1-e6ae86154f0e" xlink:to="loc_us-gaap_PlanNameDomain_5047fe3a-feaa-4f45-b7e1-e6ae86154f0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_14ecf9de-bb95-40ef-9a1c-c88c05b3d6e9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_5047fe3a-feaa-4f45-b7e1-e6ae86154f0e" xlink:to="loc_us-gaap_PlanNameDomain_14ecf9de-bb95-40ef-9a1c-c88c05b3d6e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_EquityIncentivePlanMember_7b2afb42-2383-4419-8715-e1f50ec14cd6" xlink:href="sncy-20221231.xsd#sncy_EquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_14ecf9de-bb95-40ef-9a1c-c88c05b3d6e9" xlink:to="loc_sncy_EquityIncentivePlanMember_7b2afb42-2383-4419-8715-e1f50ec14cd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_983a1118-e5e8-4c03-91ea-5170562c30d6" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3e0cf93-5a53-46e5-94da-5afa85e024d4" xlink:to="loc_srt_RangeAxis_983a1118-e5e8-4c03-91ea-5170562c30d6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_983a1118-e5e8-4c03-91ea-5170562c30d6_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_983a1118-e5e8-4c03-91ea-5170562c30d6" xlink:to="loc_srt_RangeMember_983a1118-e5e8-4c03-91ea-5170562c30d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_02a223d4-b27d-4d77-b9f8-1c4e9bb088d0" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_983a1118-e5e8-4c03-91ea-5170562c30d6" xlink:to="loc_srt_RangeMember_02a223d4-b27d-4d77-b9f8-1c4e9bb088d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_5875b1b2-b963-4e1d-a668-7b0235109f6b" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_02a223d4-b27d-4d77-b9f8-1c4e9bb088d0" xlink:to="loc_srt_MaximumMember_5875b1b2-b963-4e1d-a668-7b0235109f6b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_31e2c922-012a-4413-81f3-80b26d466fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3e0cf93-5a53-46e5-94da-5afa85e024d4" xlink:to="loc_us-gaap_AwardTypeAxis_31e2c922-012a-4413-81f3-80b26d466fa6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_31e2c922-012a-4413-81f3-80b26d466fa6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_31e2c922-012a-4413-81f3-80b26d466fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_31e2c922-012a-4413-81f3-80b26d466fa6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_96f0b22c-cfe5-4e1a-97de-65ed10763d55" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_31e2c922-012a-4413-81f3-80b26d466fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_96f0b22c-cfe5-4e1a-97de-65ed10763d55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TimeBasedStockOptionsMember_ae449b28-6a99-4604-b03c-c2a383ed3c0e" xlink:href="sncy-20221231.xsd#sncy_TimeBasedStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_96f0b22c-cfe5-4e1a-97de-65ed10763d55" xlink:to="loc_sncy_TimeBasedStockOptionsMember_ae449b28-6a99-4604-b03c-c2a383ed3c0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_6d10dd43-3685-4e5b-843a-11e95fa7b03a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_96f0b22c-cfe5-4e1a-97de-65ed10763d55" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_6d10dd43-3685-4e5b-843a-11e95fa7b03a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PerformanceBasedStockOptionsMember_c43fccc9-1dd4-41f4-8f47-03ac1302eecc" xlink:href="sncy-20221231.xsd#sncy_PerformanceBasedStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_96f0b22c-cfe5-4e1a-97de-65ed10763d55" xlink:to="loc_sncy_PerformanceBasedStockOptionsMember_c43fccc9-1dd4-41f4-8f47-03ac1302eecc" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/STOCKBASEDCOMPENSATIONStockoptionactivityDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#STOCKBASEDCOMPENSATIONStockoptionactivityDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/STOCKBASEDCOMPENSATIONStockoptionactivityDetails" xlink:type="extended" id="idb4c0180e1be405db44d462e16580a01_STOCKBASEDCOMPENSATIONStockoptionactivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_55a75b99-c7b5-4a1c-8a85-f53f246e738c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_55a75b99-c7b5-4a1c-8a85-f53f246e738c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_eeb1e904-3cfe-4fa0-b63c-e3392fadacde" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_eeb1e904-3cfe-4fa0-b63c-e3392fadacde" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_13938e56-16a1-45d2-8d04-e29e481eb354" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_13938e56-16a1-45d2-8d04-e29e481eb354" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1112e0bb-f0fc-4884-b9b4-716980312b9b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1112e0bb-f0fc-4884-b9b4-716980312b9b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_231cf1f8-3033-405c-9fbf-0af1d85f7d23" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_57a77556-6d07-455c-8ceb-ff42aaac84b7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_57a77556-6d07-455c-8ceb-ff42aaac84b7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_3903feeb-44a5-4dab-a91b-272b0c1b7ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_16aaa82e-3ff7-4fbf-8ad0-5cc819343284" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_3903feeb-44a5-4dab-a91b-272b0c1b7ce4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_06b6bd85-fadc-4d80-adeb-3390ede2d4de" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_06b6bd85-fadc-4d80-adeb-3390ede2d4de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_8f7527f1-b800-42e5-9c04-59cb86068778" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_8f7527f1-b800-42e5-9c04-59cb86068778" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_0cef7a5a-de1e-46d5-b417-f286d3d52b9f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_0cef7a5a-de1e-46d5-b417-f286d3d52b9f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_e40fc399-27d4-427e-9525-0bcce2e2e18f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_e40fc399-27d4-427e-9525-0bcce2e2e18f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_7f49a3e5-11c6-4bfd-8299-314523d97aa6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_43c82617-a821-4984-9c8a-8fc4e3e4acff" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_43c82617-a821-4984-9c8a-8fc4e3e4acff" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_dc65b664-9144-4c7b-aeec-a5a605b6b83f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_87209912-269b-4454-ab43-c95e120f92f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_dc65b664-9144-4c7b-aeec-a5a605b6b83f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_62090642-2538-4a32-ac1a-c83237a8b2a7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_62090642-2538-4a32-ac1a-c83237a8b2a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_956b1e35-826e-4ba5-93b9-51d286d93074" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_956b1e35-826e-4ba5-93b9-51d286d93074" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_1326674f-b765-4552-a87f-0dab9a18447f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_1326674f-b765-4552-a87f-0dab9a18447f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedOptionsExercisedWeightedAverageGrantDateFairValue_c9636410-e714-477d-97b2-e01f9f24ea8e" xlink:href="sncy-20221231.xsd#sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedOptionsExercisedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:to="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedOptionsExercisedWeightedAverageGrantDateFairValue_c9636410-e714-477d-97b2-e01f9f24ea8e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_3f3e8c2d-1d42-4351-b5fd-180f08bd8b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue_b257aafd-8ed1-485b-8a3e-83452db18a47" xlink:href="sncy-20221231.xsd#sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:to="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue_b257aafd-8ed1-485b-8a3e-83452db18a47" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestWeightedAverageGrantDateFairValue_f90c002e-df61-4727-a717-2a880b738287" xlink:href="sncy-20221231.xsd#sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_cc9c5401-c820-4c8d-9672-22e342fa0318" xlink:to="loc_sncy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestWeightedAverageGrantDateFairValue_f90c002e-df61-4727-a717-2a880b738287" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_fd9f7c5a-d40c-48ce-8eaf-5af63ace56df" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_fd9f7c5a-d40c-48ce-8eaf-5af63ace56df" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_d20cb03d-067b-4174-8f1c-d499412bd045" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_fd9f7c5a-d40c-48ce-8eaf-5af63ace56df" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_d20cb03d-067b-4174-8f1c-d499412bd045" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_348f477f-a186-48c3-9c64-663b160af3d7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_348f477f-a186-48c3-9c64-663b160af3d7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_0028baa1-d604-416e-9441-495935b25f4c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_348f477f-a186-48c3-9c64-663b160af3d7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_0028baa1-d604-416e-9441-495935b25f4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_e8a39e94-72d3-4bce-9b78-bb327450192f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_348f477f-a186-48c3-9c64-663b160af3d7" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_e8a39e94-72d3-4bce-9b78-bb327450192f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_a7e08857-2f9b-4942-930b-2174b7119e96" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_348f477f-a186-48c3-9c64-663b160af3d7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_a7e08857-2f9b-4942-930b-2174b7119e96" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PercentageOfStockOptionsExpectedToMeetPerformanceConditions_bfd351b0-454c-4b73-b5be-751545e9cdf2" xlink:href="sncy-20221231.xsd#sncy_PercentageOfStockOptionsExpectedToMeetPerformanceConditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:to="loc_sncy_PercentageOfStockOptionsExpectedToMeetPerformanceConditions_bfd351b0-454c-4b73-b5be-751545e9cdf2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_421cf3ac-d326-4c37-9c7c-89d0c3ad7d2f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_daffd29a-57d0-4a0f-a644-82d809fbc282" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_421cf3ac-d326-4c37-9c7c-89d0c3ad7d2f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_3b7b1759-2d01-4b62-8142-8885a3235b28" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_421cf3ac-d326-4c37-9c7c-89d0c3ad7d2f" xlink:to="loc_us-gaap_AwardTypeAxis_3b7b1759-2d01-4b62-8142-8885a3235b28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3b7b1759-2d01-4b62-8142-8885a3235b28_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_3b7b1759-2d01-4b62-8142-8885a3235b28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3b7b1759-2d01-4b62-8142-8885a3235b28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1a2a4be6-54d4-4bc0-81c2-f2c9d171d3a8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_3b7b1759-2d01-4b62-8142-8885a3235b28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1a2a4be6-54d4-4bc0-81c2-f2c9d171d3a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TimeBasedStockOptionsMember_d572930e-c68c-4f41-b193-213d4a7d5005" xlink:href="sncy-20221231.xsd#sncy_TimeBasedStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1a2a4be6-54d4-4bc0-81c2-f2c9d171d3a8" xlink:to="loc_sncy_TimeBasedStockOptionsMember_d572930e-c68c-4f41-b193-213d4a7d5005" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PerformanceBasedStockOptionsMember_8b66a27f-f63f-4784-9c79-96774bcc50eb" xlink:href="sncy-20221231.xsd#sncy_PerformanceBasedStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1a2a4be6-54d4-4bc0-81c2-f2c9d171d3a8" xlink:to="loc_sncy_PerformanceBasedStockOptionsMember_8b66a27f-f63f-4784-9c79-96774bcc50eb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/STOCKBASEDCOMPENSATIONRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#STOCKBASEDCOMPENSATIONRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/STOCKBASEDCOMPENSATIONRestrictedStockUnitsDetails" xlink:type="extended" id="i3a8a8feb9f7241b4a4e784b6a02d2ff3_STOCKBASEDCOMPENSATIONRestrictedStockUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_143e2f2f-f8b0-4246-853a-2d2697ae4527" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_f1b5ef38-b90a-4616-8ef0-d4ea31bfe6c2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_143e2f2f-f8b0-4246-853a-2d2697ae4527" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_f1b5ef38-b90a-4616-8ef0-d4ea31bfe6c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_261d3c61-a8c6-43ff-9684-610c186b34b7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_f1b5ef38-b90a-4616-8ef0-d4ea31bfe6c2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_261d3c61-a8c6-43ff-9684-610c186b34b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_bc09fdfd-f925-4e59-a2db-8c8bd6ede572" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_f1b5ef38-b90a-4616-8ef0-d4ea31bfe6c2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_bc09fdfd-f925-4e59-a2db-8c8bd6ede572" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_9231e333-44dc-4d45-bc47-28099099bd42" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_f1b5ef38-b90a-4616-8ef0-d4ea31bfe6c2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_9231e333-44dc-4d45-bc47-28099099bd42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a13839ed-0649-479a-8cc3-93a9f86cdc34" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_f1b5ef38-b90a-4616-8ef0-d4ea31bfe6c2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a13839ed-0649-479a-8cc3-93a9f86cdc34" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_79aec22a-8d99-46d3-9ce1-a81767facb04" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_a15f33dc-9620-41b2-8468-ecf33d0f1cab" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_143e2f2f-f8b0-4246-853a-2d2697ae4527" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_a15f33dc-9620-41b2-8468-ecf33d0f1cab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_f5edba44-ed59-45c7-a1ee-6d512d81f79f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_a15f33dc-9620-41b2-8468-ecf33d0f1cab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_f5edba44-ed59-45c7-a1ee-6d512d81f79f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_45973482-5310-41cd-95b8-5cffa1001405" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_a15f33dc-9620-41b2-8468-ecf33d0f1cab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_45973482-5310-41cd-95b8-5cffa1001405" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_8067c300-f7b5-4297-907d-9f3377d99825" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_a15f33dc-9620-41b2-8468-ecf33d0f1cab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_8067c300-f7b5-4297-907d-9f3377d99825" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_c5076f5e-35aa-48bc-aa4c-5e72be479bf2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_a15f33dc-9620-41b2-8468-ecf33d0f1cab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_c5076f5e-35aa-48bc-aa4c-5e72be479bf2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_bb8593d9-07b9-4398-989d-4b940dcfc466" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5a2590e2-83a8-42e8-9f96-dcf7dd029569" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_143e2f2f-f8b0-4246-853a-2d2697ae4527" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5a2590e2-83a8-42e8-9f96-dcf7dd029569" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_cbde73c4-5be1-4e2c-8f80-7bef64214a19" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5a2590e2-83a8-42e8-9f96-dcf7dd029569" xlink:to="loc_us-gaap_AwardTypeAxis_cbde73c4-5be1-4e2c-8f80-7bef64214a19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cbde73c4-5be1-4e2c-8f80-7bef64214a19_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_cbde73c4-5be1-4e2c-8f80-7bef64214a19" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cbde73c4-5be1-4e2c-8f80-7bef64214a19_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f05ead33-5bec-4cbd-9140-6826dbfe83ab" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_cbde73c4-5be1-4e2c-8f80-7bef64214a19" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f05ead33-5bec-4cbd-9140-6826dbfe83ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_a1cdada7-6133-4b55-989f-d1e99e32c147" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f05ead33-5bec-4cbd-9140-6826dbfe83ab" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_a1cdada7-6133-4b55-989f-d1e99e32c147" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/DEFINEDCONTRIBUTION401kPLANDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#DEFINEDCONTRIBUTION401kPLANDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/DEFINEDCONTRIBUTION401kPLANDetails" xlink:type="extended" id="ia41622b257484462b1afb3e4055567a0_DEFINEDCONTRIBUTION401kPLANDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_a9b4ea89-7301-424f-9a21-e1e23aec8227" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_a9b4ea89-7301-424f-9a21-e1e23aec8227" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_8620b8e5-aac7-44b4-ba9e-52cb0983e488" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_8620b8e5-aac7-44b4-ba9e-52cb0983e488" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_2a73004a-fea5-4ebd-9ad7-e49915faee7e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_2a73004a-fea5-4ebd-9ad7-e49915faee7e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NonDiscretionaryContributionBasedOnEarningsPercent_e5e0979e-cbd0-450b-9298-9a86ddbb6e31" xlink:href="sncy-20221231.xsd#sncy_NonDiscretionaryContributionBasedOnEarningsPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_sncy_NonDiscretionaryContributionBasedOnEarningsPercent_e5e0979e-cbd0-450b-9298-9a86ddbb6e31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionYearOne_1ee7e5bc-d9a7-4a59-8c09-6d9ef6b3241a" xlink:href="sncy-20221231.xsd#sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionYearOne"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionYearOne_1ee7e5bc-d9a7-4a59-8c09-6d9ef6b3241a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionYearTwo_972546c7-9e5d-4c67-b790-f81a80302504" xlink:href="sncy-20221231.xsd#sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionYearTwo_972546c7-9e5d-4c67-b790-f81a80302504" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionAmount_72fcab95-8df3-4406-8fd4-b3eba0bf2454" xlink:href="sncy-20221231.xsd#sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_sncy_DefinedContributionPlanEmployerNonDiscretionaryContributionAmount_72fcab95-8df3-4406-8fd4-b3eba0bf2454" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_ee4ef754-d90b-451a-80cc-662d4f63f9c7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_ee4ef754-d90b-451a-80cc-662d4f63f9c7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_d107eb57-03e2-41e4-98fd-f4ced09ba17f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_d107eb57-03e2-41e4-98fd-f4ced09ba17f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanTable_87c27dad-3bd9-4c41-bff0-5e835833a988" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_af45696a-e106-4e46-a79a-0444da071c5d" xlink:to="loc_us-gaap_DefinedContributionPlanTable_87c27dad-3bd9-4c41-bff0-5e835833a988" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_ea311c34-bff7-440f-a308-10cec1b4f415" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedContributionPlanTable_87c27dad-3bd9-4c41-bff0-5e835833a988" xlink:to="loc_srt_TitleOfIndividualAxis_ea311c34-bff7-440f-a308-10cec1b4f415" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_ea311c34-bff7-440f-a308-10cec1b4f415_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_ea311c34-bff7-440f-a308-10cec1b4f415" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_ea311c34-bff7-440f-a308-10cec1b4f415_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c7d9809-be05-4114-a5d1-80c342c075ba" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_ea311c34-bff7-440f-a308-10cec1b4f415" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c7d9809-be05-4114-a5d1-80c342c075ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NonPilotEmployeesMember_e9179cae-cc9c-4eb9-a497-536c02dace4b" xlink:href="sncy-20221231.xsd#sncy_NonPilotEmployeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c7d9809-be05-4114-a5d1-80c342c075ba" xlink:to="loc_sncy_NonPilotEmployeesMember_e9179cae-cc9c-4eb9-a497-536c02dace4b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PilotEmployeesMember_42eb48da-710f-4e28-8304-9625a75691d9" xlink:href="sncy-20221231.xsd#sncy_PilotEmployeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c7d9809-be05-4114-a5d1-80c342c075ba" xlink:to="loc_sncy_PilotEmployeesMember_42eb48da-710f-4e28-8304-9625a75691d9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/FUELDERIVATIVESANDRISKMANAGEMENTNarrativeDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#FUELDERIVATIVESANDRISKMANAGEMENTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/FUELDERIVATIVESANDRISKMANAGEMENTNarrativeDetails" xlink:type="extended" id="i0cbc504786c34c0ba85e8ab30d9b7052_FUELDERIVATIVESANDRISKMANAGEMENTNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_cf2aa09c-4949-4a1a-885d-c8d060851416" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_07b30025-3992-4f3b-a591-e98fe278408a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_cf2aa09c-4949-4a1a-885d-c8d060851416" xlink:to="loc_us-gaap_DerivativeNotionalAmount_07b30025-3992-4f3b-a591-e98fe278408a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_7d687175-9a61-4127-bae6-84c2a4385038" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_cf2aa09c-4949-4a1a-885d-c8d060851416" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_7d687175-9a61-4127-bae6-84c2a4385038" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_ab044097-9512-46cf-8dee-3f9972c74202" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_7d687175-9a61-4127-bae6-84c2a4385038" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_ab044097-9512-46cf-8dee-3f9972c74202" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ab044097-9512-46cf-8dee-3f9972c74202_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ab044097-9512-46cf-8dee-3f9972c74202" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ab044097-9512-46cf-8dee-3f9972c74202_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a32ec4a6-21b7-4521-89b4-27a297d815ff" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ab044097-9512-46cf-8dee-3f9972c74202" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a32ec4a6-21b7-4521-89b4-27a297d815ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_FuelDerivativeContractsMember_e16e5992-b588-4469-8b13-6833be3886ec" xlink:href="sncy-20221231.xsd#sncy_FuelDerivativeContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a32ec4a6-21b7-4521-89b4-27a297d815ff" xlink:to="loc_sncy_FuelDerivativeContractsMember_e16e5992-b588-4469-8b13-6833be3886ec" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/FUELDERIVATIVESANDRISKMANAGEMENTDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#FUELDERIVATIVESANDRISKMANAGEMENTDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/FUELDERIVATIVESANDRISKMANAGEMENTDetails" xlink:type="extended" id="id4a0f531b65846db88a0e1ed5b63a341_FUELDERIVATIVESANDRISKMANAGEMENTDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_29c5fd28-2b19-4fc8-af65-419981cac9da" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_afa7cd21-732e-4302-879f-800a087c2eff" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_29c5fd28-2b19-4fc8-af65-419981cac9da" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_afa7cd21-732e-4302-879f-800a087c2eff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_911113f0-4db6-49b0-a85c-68eb4974937c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_afa7cd21-732e-4302-879f-800a087c2eff" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_911113f0-4db6-49b0-a85c-68eb4974937c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_243758ef-c9c3-4ed6-80b6-ff3ecf92402b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_afa7cd21-732e-4302-879f-800a087c2eff" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_243758ef-c9c3-4ed6-80b6-ff3ecf92402b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_a2a9950f-9164-457f-9600-c119528e371e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_afa7cd21-732e-4302-879f-800a087c2eff" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_a2a9950f-9164-457f-9600-c119528e371e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_fb98b6c2-aeef-4e6a-b11e-17d8d8e68bea" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_d32b1020-b335-47f8-b38f-f05ef5acd76e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeGainLossOnDerivativeNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_29c5fd28-2b19-4fc8-af65-419981cac9da" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_d32b1020-b335-47f8-b38f-f05ef5acd76e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_DerivativeNonCashGainLossOnDerivativeNet_abb18c5f-d0d9-4e77-aeb6-8c45041dbebc" xlink:href="sncy-20221231.xsd#sncy_DerivativeNonCashGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_d32b1020-b335-47f8-b38f-f05ef5acd76e" xlink:to="loc_sncy_DerivativeNonCashGainLossOnDerivativeNet_abb18c5f-d0d9-4e77-aeb6-8c45041dbebc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CashPremiumsPaid_7889ee85-1ebc-4037-be1c-8ccc8be97593" xlink:href="sncy-20221231.xsd#sncy_CashPremiumsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_d32b1020-b335-47f8-b38f-f05ef5acd76e" xlink:to="loc_sncy_CashPremiumsPaid_7889ee85-1ebc-4037-be1c-8ccc8be97593" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_884bda4b-dc34-4708-be77-a252d9357c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_d32b1020-b335-47f8-b38f-f05ef5acd76e" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_884bda4b-dc34-4708-be77-a252d9357c1a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_34ff3f44-cb6f-4afc-95f8-06f6b4cd131d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_29c5fd28-2b19-4fc8-af65-419981cac9da" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_34ff3f44-cb6f-4afc-95f8-06f6b4cd131d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_fbcd436e-4c25-41f2-beec-523cb646397b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_34ff3f44-cb6f-4afc-95f8-06f6b4cd131d" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_fbcd436e-4c25-41f2-beec-523cb646397b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_fbcd436e-4c25-41f2-beec-523cb646397b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_fbcd436e-4c25-41f2-beec-523cb646397b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_fbcd436e-4c25-41f2-beec-523cb646397b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_8c791a65-f955-4e13-80f1-f6ad5cdaaf73" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_fbcd436e-4c25-41f2-beec-523cb646397b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_8c791a65-f955-4e13-80f1-f6ad5cdaaf73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_FuelDerivativeContractsMember_bf40f8fa-1194-4913-84fb-e971d534eb20" xlink:href="sncy-20221231.xsd#sncy_FuelDerivativeContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_8c791a65-f955-4e13-80f1-f6ad5cdaaf73" xlink:to="loc_sncy_FuelDerivativeContractsMember_bf40f8fa-1194-4913-84fb-e971d534eb20" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/INVESTMENTSDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#INVESTMENTSDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/INVESTMENTSDetails" xlink:type="extended" id="i94ff7dd788004dc1b7fed96e1776e2b5_INVESTMENTSDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2bdb903c-77f9-484b-aea4-e56e80117c49" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAfterAllowanceForCreditLoss_d3b132a7-6f64-48ec-b43b-8e3631127003" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2bdb903c-77f9-484b-aea4-e56e80117c49" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAfterAllowanceForCreditLoss_d3b132a7-6f64-48ec-b43b-8e3631127003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_dc666b3f-921d-4ef4-95a4-4eeda00ef77d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2bdb903c-77f9-484b-aea4-e56e80117c49" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_dc666b3f-921d-4ef4-95a4-4eeda00ef77d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_072f48f0-fe10-4055-9df3-2cecce690cbd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2bdb903c-77f9-484b-aea4-e56e80117c49" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_072f48f0-fe10-4055-9df3-2cecce690cbd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_25b5e331-81f6-438e-a211-b2af4aaf3326" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2bdb903c-77f9-484b-aea4-e56e80117c49" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_25b5e331-81f6-438e-a211-b2af4aaf3326" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecurities_0f3dd569-391a-4496-be9b-2cbbe0154527" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2bdb903c-77f9-484b-aea4-e56e80117c49" xlink:to="loc_us-gaap_DebtSecurities_0f3dd569-391a-4496-be9b-2cbbe0154527" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_a228357b-d0a3-4a43-819c-f84a618d5ae3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2bdb903c-77f9-484b-aea4-e56e80117c49" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_a228357b-d0a3-4a43-819c-f84a618d5ae3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_4a15cff3-9a0a-4eaa-b02f-81a2a14170d0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_a228357b-d0a3-4a43-819c-f84a618d5ae3" xlink:to="loc_us-gaap_FinancialInstrumentAxis_4a15cff3-9a0a-4eaa-b02f-81a2a14170d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4a15cff3-9a0a-4eaa-b02f-81a2a14170d0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_4a15cff3-9a0a-4eaa-b02f-81a2a14170d0" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4a15cff3-9a0a-4eaa-b02f-81a2a14170d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bd49a201-540b-4b1d-b97e-3916dea23ca0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_4a15cff3-9a0a-4eaa-b02f-81a2a14170d0" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bd49a201-540b-4b1d-b97e-3916dea23ca0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesMember_c1eb867e-8f09-4ba2-b898-a0a672ff0ae5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bd49a201-540b-4b1d-b97e-3916dea23ca0" xlink:to="loc_us-gaap_DebtSecuritiesMember_c1eb867e-8f09-4ba2-b898-a0a672ff0ae5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_c1eeed9e-2e49-44ad-b2d8-d47ae65c0728" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bd49a201-540b-4b1d-b97e-3916dea23ca0" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_c1eeed9e-2e49-44ad-b2d8-d47ae65c0728" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_3fef4e98-71c9-433a-820d-d05002c8f4eb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bd49a201-540b-4b1d-b97e-3916dea23ca0" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_3fef4e98-71c9-433a-820d-d05002c8f4eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_bc853a6f-da17-463f-a3b7-5449020b58b2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CertificatesOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bd49a201-540b-4b1d-b97e-3916dea23ca0" xlink:to="loc_us-gaap_CertificatesOfDepositMember_bc853a6f-da17-463f-a3b7-5449020b58b2" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/FAIRVALUEMEASUREMENTSDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#FAIRVALUEMEASUREMENTSDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/FAIRVALUEMEASUREMENTSDetails" xlink:type="extended" id="iafdd51269ee744dbbb51db0f1072ab9a_FAIRVALUEMEASUREMENTSDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f546d817-3fdd-48b8-bb36-6b8f87a7286e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_9af7f616-0380-4b57-bbe5-c905a4867393" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f546d817-3fdd-48b8-bb36-6b8f87a7286e" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_9af7f616-0380-4b57-bbe5-c905a4867393" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_add742d9-6595-486c-b661-0d9ae9454774" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f546d817-3fdd-48b8-bb36-6b8f87a7286e" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_add742d9-6595-486c-b661-0d9ae9454774" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_4669b4b9-3f3d-4d76-968e-57184fc149b3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f546d817-3fdd-48b8-bb36-6b8f87a7286e" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_4669b4b9-3f3d-4d76-968e-57184fc149b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e5a9a55-2bff-45ef-9163-4326bff5ee1b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f546d817-3fdd-48b8-bb36-6b8f87a7286e" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e5a9a55-2bff-45ef-9163-4326bff5ee1b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e426819-9d57-447b-9406-38701c9e1b07" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e5a9a55-2bff-45ef-9163-4326bff5ee1b" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e426819-9d57-447b-9406-38701c9e1b07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_8e426819-9d57-447b-9406-38701c9e1b07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e426819-9d57-447b-9406-38701c9e1b07" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_8e426819-9d57-447b-9406-38701c9e1b07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1f6b9f07-5e04-46f7-9588-a83aa732f420" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e426819-9d57-447b-9406-38701c9e1b07" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1f6b9f07-5e04-46f7-9588-a83aa732f420" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_e8bf77db-fedb-4310-b384-69ae60c60e4a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_1f6b9f07-5e04-46f7-9588-a83aa732f420" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_e8bf77db-fedb-4310-b384-69ae60c60e4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d3156c70-e92a-41a2-a4e5-ec22308ec0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e5a9a55-2bff-45ef-9163-4326bff5ee1b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d3156c70-e92a-41a2-a4e5-ec22308ec0bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d3156c70-e92a-41a2-a4e5-ec22308ec0bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d3156c70-e92a-41a2-a4e5-ec22308ec0bb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d3156c70-e92a-41a2-a4e5-ec22308ec0bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6d1beca7-e029-4680-95c8-c33343c34e4e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d3156c70-e92a-41a2-a4e5-ec22308ec0bb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6d1beca7-e029-4680-95c8-c33343c34e4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_e8215c88-ebc3-4b7f-a62a-1c0a1e3541ca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6d1beca7-e029-4680-95c8-c33343c34e4e" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_e8215c88-ebc3-4b7f-a62a-1c0a1e3541ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_6a2b2f14-d382-43c3-8913-b2f82907a30f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6d1beca7-e029-4680-95c8-c33343c34e4e" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_6a2b2f14-d382-43c3-8913-b2f82907a30f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_0e3eb4fd-de50-4e4d-a41e-bb3ad6e8a677" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6d1beca7-e029-4680-95c8-c33343c34e4e" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_0e3eb4fd-de50-4e4d-a41e-bb3ad6e8a677" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_14fc8250-6e49-47d6-89c9-d23697b915ca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e5a9a55-2bff-45ef-9163-4326bff5ee1b" xlink:to="loc_us-gaap_FinancialInstrumentAxis_14fc8250-6e49-47d6-89c9-d23697b915ca" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_14fc8250-6e49-47d6-89c9-d23697b915ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_14fc8250-6e49-47d6-89c9-d23697b915ca" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_14fc8250-6e49-47d6-89c9-d23697b915ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_03c132f3-5f7f-4b00-b251-5758b7de2cb3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_14fc8250-6e49-47d6-89c9-d23697b915ca" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_03c132f3-5f7f-4b00-b251-5758b7de2cb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesMember_3500c1a7-eb9d-4539-a07b-6ea45e57f427" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_03c132f3-5f7f-4b00-b251-5758b7de2cb3" xlink:to="loc_us-gaap_DebtSecuritiesMember_3500c1a7-eb9d-4539-a07b-6ea45e57f427" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_a53c75d4-43fd-4e36-a50c-5b7d74dc064d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_03c132f3-5f7f-4b00-b251-5758b7de2cb3" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_a53c75d4-43fd-4e36-a50c-5b7d74dc064d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_04104558-350a-44ac-88b4-620af266d5c1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_03c132f3-5f7f-4b00-b251-5758b7de2cb3" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_04104558-350a-44ac-88b4-620af266d5c1" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/INCOMETAXESAdditionalInformationDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#INCOMETAXESAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/INCOMETAXESAdditionalInformationDetails" xlink:type="extended" id="i192311deb7814f35ac8fd852c2e22de3_INCOMETAXESAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExaminationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic_aafe955e-8b4f-4c4b-a35f-9c1d77ec064c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic_aafe955e-8b4f-4c4b-a35f-9c1d77ec064c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal_7291ad3c-fb08-48ee-999b-7749994c9963" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal_7291ad3c-fb08-48ee-999b-7749994c9963" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_ef113c04-c866-4b07-bb38-00d2de67d9c3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_ef113c04-c866-4b07-bb38-00d2de67d9c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PercentageOfCashSavingsInFederalAndStateIncomeTaxesThatPreIPOStockholdersRightToReceive_89928b39-0410-41df-8f89-a7ed1321dda4" xlink:href="sncy-20221231.xsd#sncy_PercentageOfCashSavingsInFederalAndStateIncomeTaxesThatPreIPOStockholdersRightToReceive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_sncy_PercentageOfCashSavingsInFederalAndStateIncomeTaxesThatPreIPOStockholdersRightToReceive_89928b39-0410-41df-8f89-a7ed1321dda4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TaxReceivableAgreementPercentageOfBenefitOnCashSavingsRetainedByCompany_c2ff1287-b999-44ed-b406-724aef8557ca" xlink:href="sncy-20221231.xsd#sncy_TaxReceivableAgreementPercentageOfBenefitOnCashSavingsRetainedByCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_sncy_TaxReceivableAgreementPercentageOfBenefitOnCashSavingsRetainedByCompany_c2ff1287-b999-44ed-b406-724aef8557ca" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_TaxReceivableAgreementLiabilityNoncurrent_cf91f4c8-2c49-45cb-8ca4-4e607b49c9bb" xlink:href="sncy-20221231.xsd#sncy_TaxReceivableAgreementLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_sncy_TaxReceivableAgreementLiabilityNoncurrent_cf91f4c8-2c49-45cb-8ca4-4e607b49c9bb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_IncreaseDecreaseInTaxReceivableAgreementLiability_b4306957-5422-4107-ab5b-288b98af96bb" xlink:href="sncy-20221231.xsd#sncy_IncreaseDecreaseInTaxReceivableAgreementLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_sncy_IncreaseDecreaseInTaxReceivableAgreementLiability_b4306957-5422-4107-ab5b-288b98af96bb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationTable_0fe1985f-aed3-4c90-b3cc-0684816caa86" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExaminationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_568a2d05-54d2-46d9-bf12-e899292197c8" xlink:to="loc_us-gaap_IncomeTaxExaminationTable_0fe1985f-aed3-4c90-b3cc-0684816caa86" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_44b7c83a-3379-4026-b5e1-79587efad1c2" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_0fe1985f-aed3-4c90-b3cc-0684816caa86" xlink:to="loc_srt_RangeAxis_44b7c83a-3379-4026-b5e1-79587efad1c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_44b7c83a-3379-4026-b5e1-79587efad1c2_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_44b7c83a-3379-4026-b5e1-79587efad1c2" xlink:to="loc_srt_RangeMember_44b7c83a-3379-4026-b5e1-79587efad1c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e851df26-6b7c-4aae-9991-4016347e476a" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_44b7c83a-3379-4026-b5e1-79587efad1c2" xlink:to="loc_srt_RangeMember_e851df26-6b7c-4aae-9991-4016347e476a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_287193c9-92f0-4c9c-aba7-0763c00b7427" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e851df26-6b7c-4aae-9991-4016347e476a" xlink:to="loc_srt_MaximumMember_287193c9-92f0-4c9c-aba7-0763c00b7427" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/STOCKHOLDERSEQUITYDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#STOCKHOLDERSEQUITYDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/STOCKHOLDERSEQUITYDetails" xlink:type="extended" id="i3bb146d6b38740bcb2c17a42b0a1689e_STOCKHOLDERSEQUITYDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_a7a36ecb-29f7-4ba1-bd29-50517fd25b06" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_a7a36ecb-29f7-4ba1-bd29-50517fd25b06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_7687de85-77ca-43ac-94b2-292d6eb2f768" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_7687de85-77ca-43ac-94b2-292d6eb2f768" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_8743660d-71f1-4320-89b7-7de6cca4c0b4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_8743660d-71f1-4320-89b7-7de6cca4c0b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_StocksRepurchasedDuringPeriodSharesTotal_28947904-bdbd-4b62-afc0-3ee8965bd5d2" xlink:href="sncy-20221231.xsd#sncy_StocksRepurchasedDuringPeriodSharesTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:to="loc_sncy_StocksRepurchasedDuringPeriodSharesTotal_28947904-bdbd-4b62-afc0-3ee8965bd5d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesInitialPricePaidPerShare_1dec8eac-d6a9-4b41-b636-97dbfb08ea75" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AcceleratedShareRepurchasesInitialPricePaidPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesInitialPricePaidPerShare_1dec8eac-d6a9-4b41-b636-97dbfb08ea75" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_a4c6d8c8-fa51-48cd-a066-2ffd17902f20" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_a4c6d8c8-fa51-48cd-a066-2ffd17902f20" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_4680e1a1-bd9b-4ea9-a1ac-5bf699afc313" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_5ca784cc-2530-4334-904b-c51919ac6299" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_4680e1a1-bd9b-4ea9-a1ac-5bf699afc313" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_2c8f3eba-502c-4ed2-847b-35e0ea3925b3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4680e1a1-bd9b-4ea9-a1ac-5bf699afc313" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_2c8f3eba-502c-4ed2-847b-35e0ea3925b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_2c8f3eba-502c-4ed2-847b-35e0ea3925b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_2c8f3eba-502c-4ed2-847b-35e0ea3925b3" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_2c8f3eba-502c-4ed2-847b-35e0ea3925b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_961d1889-c7e9-48b6-a45e-b0a6858c6e48" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_2c8f3eba-502c-4ed2-847b-35e0ea3925b3" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_961d1889-c7e9-48b6-a45e-b0a6858c6e48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_A2022RepurchaseProgramMember_bb155158-33db-4c41-a092-fe2b077477f6" xlink:href="sncy-20221231.xsd#sncy_A2022RepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_961d1889-c7e9-48b6-a45e-b0a6858c6e48" xlink:to="loc_sncy_A2022RepurchaseProgramMember_bb155158-33db-4c41-a092-fe2b077477f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_5d4d1b41-f50f-4038-be85-9adc7a285415" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4680e1a1-bd9b-4ea9-a1ac-5bf699afc313" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_5d4d1b41-f50f-4038-be85-9adc7a285415" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_5d4d1b41-f50f-4038-be85-9adc7a285415_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5d4d1b41-f50f-4038-be85-9adc7a285415" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_5d4d1b41-f50f-4038-be85-9adc7a285415_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_dee4f916-f8f3-4907-8165-8eb6a80f3205" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5d4d1b41-f50f-4038-be85-9adc7a285415" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_dee4f916-f8f3-4907-8165-8eb6a80f3205" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_5cf4c7f7-95ee-431a-96c6-5b8f5fe77942" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_dee4f916-f8f3-4907-8165-8eb6a80f3205" xlink:to="loc_us-gaap_SubsequentEventMember_5cf4c7f7-95ee-431a-96c6-5b8f5fe77942" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#COMMITMENTSANDCONTINGENCIESDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="extended" id="i2788c1ca79ad46d682ee103e628c6a4d_COMMITMENTSANDCONTINGENCIESDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems_fe33adda-ad54-4f65-a6c0-9865f15eab27" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfAircraftToLease_55512248-4a82-47e1-a542-73ccca0a0e17" xlink:href="sncy-20221231.xsd#sncy_NumberOfAircraftToLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems_fe33adda-ad54-4f65-a6c0-9865f15eab27" xlink:to="loc_sncy_NumberOfAircraftToLease_55512248-4a82-47e1-a542-73ccca0a0e17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_5ab1bb4d-a835-433d-8a3a-6c1d20990169" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems_fe33adda-ad54-4f65-a6c0-9865f15eab27" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_5ab1bb4d-a835-433d-8a3a-6c1d20990169" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_9583865f-f547-443e-b79d-3bdbfa29bd81" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems_fe33adda-ad54-4f65-a6c0-9865f15eab27" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_9583865f-f547-443e-b79d-3bdbfa29bd81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligation_077cf51e-1768-4020-81be-ac1f1ab6751f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractualObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems_fe33adda-ad54-4f65-a6c0-9865f15eab27" xlink:to="loc_us-gaap_ContractualObligation_077cf51e-1768-4020-81be-ac1f1ab6751f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentTable_cbf4ccd7-2e49-46fc-80aa-79a1acda90f3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PurchaseCommitmentExcludingLongtermCommitmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems_fe33adda-ad54-4f65-a6c0-9865f15eab27" xlink:to="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentTable_cbf4ccd7-2e49-46fc-80aa-79a1acda90f3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_3c8c7e6e-b652-4262-82be-53a50a065995" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PurchaseCommitmentExcludingLongtermCommitmentTable_cbf4ccd7-2e49-46fc-80aa-79a1acda90f3" xlink:to="loc_us-gaap_OtherCommitmentsAxis_3c8c7e6e-b652-4262-82be-53a50a065995" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_3c8c7e6e-b652-4262-82be-53a50a065995_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_3c8c7e6e-b652-4262-82be-53a50a065995" xlink:to="loc_us-gaap_OtherCommitmentsDomain_3c8c7e6e-b652-4262-82be-53a50a065995_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_8819c5f2-9f83-44fd-872e-56ddcce733a0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_3c8c7e6e-b652-4262-82be-53a50a065995" xlink:to="loc_us-gaap_OtherCommitmentsDomain_8819c5f2-9f83-44fd-872e-56ddcce733a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsMember_3a38833f-16bd-4b06-bc90-3668e441d7b6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommitmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_8819c5f2-9f83-44fd-872e-56ddcce733a0" xlink:to="loc_us-gaap_CommitmentsMember_3a38833f-16bd-4b06-bc90-3668e441d7b6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/OPERATINGSEGMENTSDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#OPERATINGSEGMENTSDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/OPERATINGSEGMENTSDetails" xlink:type="extended" id="i10ca78a9363c4292a4dd86fdd6a9a75a_OPERATINGSEGMENTSDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_7d9dbbf7-aaa8-4271-8167-d83e94c33ae5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_NumberOfOperatingSegments_7d9dbbf7-aaa8-4271-8167-d83e94c33ae5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NumberOfInternalPassengerGroups_86928867-fb69-4afd-903a-4ac28d31030e" xlink:href="sncy-20221231.xsd#sncy_NumberOfInternalPassengerGroups"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_sncy_NumberOfInternalPassengerGroups_86928867-fb69-4afd-903a-4ac28d31030e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_31be27fe-c410-4eac-86f5-88f8bc73a66d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_31be27fe-c410-4eac-86f5-88f8bc73a66d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NonFuelOperatingExpenses_6dd30f6c-3b1e-4150-964a-834daa544ef8" xlink:href="sncy-20221231.xsd#sncy_NonFuelOperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_sncy_NonFuelOperatingExpenses_6dd30f6c-3b1e-4150-964a-834daa544ef8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FuelCosts_78ca2ace-1584-4ba8-a28b-cd2f56aab7bd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FuelCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_FuelCosts_78ca2ace-1584-4ba8-a28b-cd2f56aab7bd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusualOrInfrequentItemNetGainLoss_57e94d49-47a7-4715-92bb-181840eb9e48" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnusualOrInfrequentItemNetGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_UnusualOrInfrequentItemNetGainLoss_57e94d49-47a7-4715-92bb-181840eb9e48" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_3bcc504e-d55a-4113-9822-8091322dae45" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_CostsAndExpenses_3bcc504e-d55a-4113-9822-8091322dae45" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_9cf02911-46e9-4568-aaef-31dedb1e83ff" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_OperatingIncomeLoss_9cf02911-46e9-4568-aaef-31dedb1e83ff" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_e25e281d-feea-438d-a7d5-e39eb61233ca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_InvestmentIncomeInterest_e25e281d-feea-438d-a7d5-e39eb61233ca" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_55b1092c-4526-42f2-9b19-739d085807a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_InterestExpense_55b1092c-4526-42f2-9b19-739d085807a3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_7d89c12b-4b05-4555-a361-52c608d16048" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_7d89c12b-4b05-4555-a361-52c608d16048" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_36333c24-4f76-44ba-877a-0d13a42d6178" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_36333c24-4f76-44ba-877a-0d13a42d6178" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c360b00c-de79-4e95-9458-26a71dbc1a5d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0d09eb56-ba42-4cac-9f66-def9f09730f8" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c360b00c-de79-4e95-9458-26a71dbc1a5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_684a2d53-9ebe-4eab-9ba8-0882f4d36f85" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c360b00c-de79-4e95-9458-26a71dbc1a5d" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_684a2d53-9ebe-4eab-9ba8-0882f4d36f85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_684a2d53-9ebe-4eab-9ba8-0882f4d36f85_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_684a2d53-9ebe-4eab-9ba8-0882f4d36f85" xlink:to="loc_us-gaap_SegmentDomain_684a2d53-9ebe-4eab-9ba8-0882f4d36f85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9cab0e1f-5213-4c65-8a0c-e8c22d3fb105" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_684a2d53-9ebe-4eab-9ba8-0882f4d36f85" xlink:to="loc_us-gaap_SegmentDomain_9cab0e1f-5213-4c65-8a0c-e8c22d3fb105" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_PassengerSegmentMember_1118ac6e-f8a5-40d7-adbe-4a31ba3e6437" xlink:href="sncy-20221231.xsd#sncy_PassengerSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9cab0e1f-5213-4c65-8a0c-e8c22d3fb105" xlink:to="loc_sncy_PassengerSegmentMember_1118ac6e-f8a5-40d7-adbe-4a31ba3e6437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_CargoMember_a7e1c54a-a9b4-4aa3-93b9-a1afe6cf18a4" xlink:href="sncy-20221231.xsd#sncy_CargoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9cab0e1f-5213-4c65-8a0c-e8c22d3fb105" xlink:to="loc_sncy_CargoMember_a7e1c54a-a9b4-4aa3-93b9-a1afe6cf18a4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/PARENTCOMPANYFINANCIALSTATEMENTSImpactofRevisiononPreviouslyIssuedCondensedParentCompanyDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#PARENTCOMPANYFINANCIALSTATEMENTSImpactofRevisiononPreviouslyIssuedCondensedParentCompanyDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/PARENTCOMPANYFINANCIALSTATEMENTSImpactofRevisiononPreviouslyIssuedCondensedParentCompanyDetails" xlink:type="extended" id="icc3cbfbdead04b99af77c71a937a15bc_PARENTCOMPANYFINANCIALSTATEMENTSImpactofRevisiononPreviouslyIssuedCondensedParentCompanyDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_2028a1b8-c0c9-4fec-ac56-21bcf96f1579" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementOfFinancialPositionAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_2028a1b8-c0c9-4fec-ac56-21bcf96f1579" xlink:to="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_bc70302f-77b8-4e20-838a-535070b4f664" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_bc70302f-77b8-4e20-838a-535070b4f664" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OtherAssetsNoncurrentTotal_bf22d19f-c215-4f80-950a-7612e0114057" xlink:href="sncy-20221231.xsd#sncy_OtherAssetsNoncurrentTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:to="loc_sncy_OtherAssetsNoncurrentTotal_bf22d19f-c215-4f80-950a-7612e0114057" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_eccd0164-f730-4e7f-a3ae-95a9ed653dcc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:to="loc_us-gaap_Assets_eccd0164-f730-4e7f-a3ae-95a9ed653dcc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_2f3fd916-e90e-456a-b957-f2be3f75ae16" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_2f3fd916-e90e-456a-b957-f2be3f75ae16" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9ae4175a-1183-4012-8f73-d2513dd8a6d5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9ae4175a-1183-4012-8f73-d2513dd8a6d5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_f3a979fc-4fae-4e20-a2bb-9abdb2b9a1dd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_6f0e8e2b-d37b-47e2-b8b0-534443496ae0" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_f3a979fc-4fae-4e20-a2bb-9abdb2b9a1dd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract_6cc30e15-8b09-4099-b1ef-fbdfeaa33ea6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_2028a1b8-c0c9-4fec-ac56-21bcf96f1579" xlink:to="loc_us-gaap_IncomeStatementAbstract_6cc30e15-8b09-4099-b1ef-fbdfeaa33ea6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_5e8056cd-18d5-4ff2-ba19-54bcff8b0cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromSubsidiariesNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_6cc30e15-8b09-4099-b1ef-fbdfeaa33ea6" xlink:to="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_5e8056cd-18d5-4ff2-ba19-54bcff8b0cb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_4d5746c3-aca1-49ef-ad38-a0e5a0cbda13" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_6cc30e15-8b09-4099-b1ef-fbdfeaa33ea6" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_4d5746c3-aca1-49ef-ad38-a0e5a0cbda13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_b40e3392-57eb-44bf-8354-022b38dcd3e6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_6cc30e15-8b09-4099-b1ef-fbdfeaa33ea6" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_b40e3392-57eb-44bf-8354-022b38dcd3e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_23ec93f4-f2e4-4dd1-b3d6-c66c2eb5d9ba" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_6cc30e15-8b09-4099-b1ef-fbdfeaa33ea6" xlink:to="loc_us-gaap_NetIncomeLoss_23ec93f4-f2e4-4dd1-b3d6-c66c2eb5d9ba" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_26154c3b-014a-494e-9c51-000dbb09bc49" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_2028a1b8-c0c9-4fec-ac56-21bcf96f1579" xlink:to="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_26154c3b-014a-494e-9c51-000dbb09bc49" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAxis_87af0b33-9f2d-4203-8f65-7433a6be08cc" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_26154c3b-014a-494e-9c51-000dbb09bc49" xlink:to="loc_srt_RestatementAxis_87af0b33-9f2d-4203-8f65-7433a6be08cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_87af0b33-9f2d-4203-8f65-7433a6be08cc_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_87af0b33-9f2d-4203-8f65-7433a6be08cc" xlink:to="loc_srt_RestatementDomain_87af0b33-9f2d-4203-8f65-7433a6be08cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_1491d6ed-d782-4af6-9849-d47c2255db6d" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_87af0b33-9f2d-4203-8f65-7433a6be08cc" xlink:to="loc_srt_RestatementDomain_1491d6ed-d782-4af6-9849-d47c2255db6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioPreviouslyReportedMember_ba208783-7240-4118-b8ca-c6fc860aaaf6" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScenarioPreviouslyReportedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_1491d6ed-d782-4af6-9849-d47c2255db6d" xlink:to="loc_srt_ScenarioPreviouslyReportedMember_ba208783-7240-4118-b8ca-c6fc860aaaf6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAdjustmentMember_9f6bb6ce-4530-42ef-8271-81c1f73724e6" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_1491d6ed-d782-4af6-9849-d47c2255db6d" xlink:to="loc_srt_RestatementAdjustmentMember_9f6bb6ce-4530-42ef-8271-81c1f73724e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_398167cb-23d2-4d4b-8451-da708c502997" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_26154c3b-014a-494e-9c51-000dbb09bc49" xlink:to="loc_srt_ConsolidatedEntitiesAxis_398167cb-23d2-4d4b-8451-da708c502997" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_398167cb-23d2-4d4b-8451-da708c502997_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_398167cb-23d2-4d4b-8451-da708c502997" xlink:to="loc_srt_ConsolidatedEntitiesDomain_398167cb-23d2-4d4b-8451-da708c502997_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_3aad893a-b57d-43c9-bd08-cb49847283e1" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_398167cb-23d2-4d4b-8451-da708c502997" xlink:to="loc_srt_ConsolidatedEntitiesDomain_3aad893a-b57d-43c9-bd08-cb49847283e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_f5fbd65d-ad3f-4cae-98ce-18f223b0bcda" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_3aad893a-b57d-43c9-bd08-cb49847283e1" xlink:to="loc_srt_ParentCompanyMember_f5fbd65d-ad3f-4cae-98ce-18f223b0bcda" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/PARENTCOMPANYFINANCIALSTATEMENTSBalanceSheetsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#PARENTCOMPANYFINANCIALSTATEMENTSBalanceSheetsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/PARENTCOMPANYFINANCIALSTATEMENTSBalanceSheetsDetails" xlink:type="extended" id="i5893a43925fc4545bca455c5f320b68f_PARENTCOMPANYFINANCIALSTATEMENTSBalanceSheetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_75fc9716-c8a5-42a9-8869-decbc10e7187" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CondensedBalanceSheetStatementsCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_3be5e6e9-06cd-4509-a971-b5cdd96b9d94" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_75fc9716-c8a5-42a9-8869-decbc10e7187" xlink:to="loc_us-gaap_AssetsAbstract_3be5e6e9-06cd-4509-a971-b5cdd96b9d94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_54e1dae2-f410-4e3a-abf4-926522824c2b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3be5e6e9-06cd-4509-a971-b5cdd96b9d94" xlink:to="loc_us-gaap_AssetsCurrentAbstract_54e1dae2-f410-4e3a-abf4-926522824c2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_70eb8527-a048-4f1d-9441-c0f5b5e0fccd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_54e1dae2-f410-4e3a-abf4-926522824c2b" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_70eb8527-a048-4f1d-9441-c0f5b5e0fccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_d5590c2d-4a44-439e-b34a-4d5eca1970d7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_54e1dae2-f410-4e3a-abf4-926522824c2b" xlink:to="loc_us-gaap_AssetsCurrent_d5590c2d-4a44-439e-b34a-4d5eca1970d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsAbstract_f05c7e04-bd59-48dd-8d8f-35f1d54660e1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3be5e6e9-06cd-4509-a971-b5cdd96b9d94" xlink:to="loc_us-gaap_OtherAssetsAbstract_f05c7e04-bd59-48dd-8d8f-35f1d54660e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_70378fbd-93f6-4a0f-8380-9a04af85b220" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_f05c7e04-bd59-48dd-8d8f-35f1d54660e1" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_70378fbd-93f6-4a0f-8380-9a04af85b220" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_OtherAssetsNoncurrentTotal_45fd84e5-5432-4074-b8ca-418e3ce870bb" xlink:href="sncy-20221231.xsd#sncy_OtherAssetsNoncurrentTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsAbstract_f05c7e04-bd59-48dd-8d8f-35f1d54660e1" xlink:to="loc_sncy_OtherAssetsNoncurrentTotal_45fd84e5-5432-4074-b8ca-418e3ce870bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_6b081ed4-3c99-4a48-b7c4-e0f51452825e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3be5e6e9-06cd-4509-a971-b5cdd96b9d94" xlink:to="loc_us-gaap_Assets_6b081ed4-3c99-4a48-b7c4-e0f51452825e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_adf39db2-3ac9-4fde-ba77-b2e81d802e36" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_75fc9716-c8a5-42a9-8869-decbc10e7187" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_adf39db2-3ac9-4fde-ba77-b2e81d802e36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_b588a48f-7f83-4d04-b647-8639c4feab75" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_adf39db2-3ac9-4fde-ba77-b2e81d802e36" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_b588a48f-7f83-4d04-b647-8639c4feab75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_c71b14ea-7963-48ec-ae98-33be33857622" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_b588a48f-7f83-4d04-b647-8639c4feab75" xlink:to="loc_us-gaap_AccountsPayableCurrent_c71b14ea-7963-48ec-ae98-33be33857622" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_dd351f98-3e7e-4d42-95c3-2086f42fae99" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_b588a48f-7f83-4d04-b647-8639c4feab75" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_dd351f98-3e7e-4d42-95c3-2086f42fae99" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_0b5b2485-1fa1-4d16-8af6-fea3ea321481" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_b588a48f-7f83-4d04-b647-8639c4feab75" xlink:to="loc_us-gaap_LiabilitiesCurrent_0b5b2485-1fa1-4d16-8af6-fea3ea321481" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_1b96c938-311d-4a70-9223-677144984839" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_adf39db2-3ac9-4fde-ba77-b2e81d802e36" xlink:to="loc_us-gaap_LiabilitiesAbstract_1b96c938-311d-4a70-9223-677144984839" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_264e871d-bf71-4dba-a8af-a9c82f9dd4ca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_1b96c938-311d-4a70-9223-677144984839" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_264e871d-bf71-4dba-a8af-a9c82f9dd4ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_414684d8-5232-4d2e-bd98-1b4563c2c65c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_1b96c938-311d-4a70-9223-677144984839" xlink:to="loc_us-gaap_Liabilities_414684d8-5232-4d2e-bd98-1b4563c2c65c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityNoteAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_adf39db2-3ac9-4fde-ba77-b2e81d802e36" xlink:to="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_3d90f3bf-36ea-4ca0-9b63-b14ed7b8fb83" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:to="loc_us-gaap_CommonStockValue_3d90f3bf-36ea-4ca0-9b63-b14ed7b8fb83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock_7d9d5143-ba3b-4593-af33-7ab97120ca5c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:to="loc_us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock_7d9d5143-ba3b-4593-af33-7ab97120ca5c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_6c259c9c-64a0-44ec-95d2-6c2f180d4cff" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:to="loc_us-gaap_AdditionalPaidInCapital_6c259c9c-64a0-44ec-95d2-6c2f180d4cff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_a2095e9f-3e3c-42cd-8a8d-72a95e8926cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_a2095e9f-3e3c-42cd-8a8d-72a95e8926cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_0f234533-e337-4afd-ba82-76fffe6f9b44" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_0f234533-e337-4afd-ba82-76fffe6f9b44" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_65296b46-14ee-4f7a-91ce-e0bb617c3902" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_65296b46-14ee-4f7a-91ce-e0bb617c3902" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_83784973-a28b-4782-9440-cf25d2d921f3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_f5c8b234-d880-4c62-865f-8dad6b62fe64" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_83784973-a28b-4782-9440-cf25d2d921f3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedBalanceSheetStatementTable_c86ee533-5a92-410a-b5f6-5af982e1038b" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CondensedBalanceSheetStatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_75fc9716-c8a5-42a9-8869-decbc10e7187" xlink:to="loc_srt_CondensedBalanceSheetStatementTable_c86ee533-5a92-410a-b5f6-5af982e1038b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_f5a84e21-95ba-4e8c-b597-e87f73e077bd" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_CondensedBalanceSheetStatementTable_c86ee533-5a92-410a-b5f6-5af982e1038b" xlink:to="loc_srt_ConsolidatedEntitiesAxis_f5a84e21-95ba-4e8c-b597-e87f73e077bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_f5a84e21-95ba-4e8c-b597-e87f73e077bd_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_f5a84e21-95ba-4e8c-b597-e87f73e077bd" xlink:to="loc_srt_ConsolidatedEntitiesDomain_f5a84e21-95ba-4e8c-b597-e87f73e077bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_3a41191e-2252-4f0d-ba85-28b17a6681d1" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_f5a84e21-95ba-4e8c-b597-e87f73e077bd" xlink:to="loc_srt_ConsolidatedEntitiesDomain_3a41191e-2252-4f0d-ba85-28b17a6681d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_574832c7-e997-4133-b613-7d208b5f5a52" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_3a41191e-2252-4f0d-ba85-28b17a6681d1" xlink:to="loc_srt_ParentCompanyMember_574832c7-e997-4133-b613-7d208b5f5a52" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncountry.com/role/PARENTCOMPANYFINANCIALSTATEMENTSStatementsofOperationsDetails" xlink:type="simple" xlink:href="sncy-20221231.xsd#PARENTCOMPANYFINANCIALSTATEMENTSStatementsofOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.suncountry.com/role/PARENTCOMPANYFINANCIALSTATEMENTSStatementsofOperationsDetails" xlink:type="extended" id="i2bd6882ee7c6429abe5f4172d0b21f30_PARENTCOMPANYFINANCIALSTATEMENTSStatementsofOperationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CondensedIncomeStatementsCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_00e971ae-b8f3-4c13-bdd1-aeaa6af5b994" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_us-gaap_OperatingExpensesAbstract_00e971ae-b8f3-4c13-bdd1-aeaa6af5b994" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_4a95b4ff-77c3-4535-b345-2c4ad2e47ba7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_00e971ae-b8f3-4c13-bdd1-aeaa6af5b994" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_4a95b4ff-77c3-4535-b345-2c4ad2e47ba7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_582e9193-57f1-4be0-bf7a-8d45343b14ff" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_00e971ae-b8f3-4c13-bdd1-aeaa6af5b994" xlink:to="loc_us-gaap_CostsAndExpenses_582e9193-57f1-4be0-bf7a-8d45343b14ff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_fdcc3fa1-1a2c-46a6-a600-a11905675f95" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_00e971ae-b8f3-4c13-bdd1-aeaa6af5b994" xlink:to="loc_us-gaap_OperatingIncomeLoss_fdcc3fa1-1a2c-46a6-a600-a11905675f95" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sncy_NonOperatingIncomeExpenseAbstract_bcf923a8-473f-4916-adf0-e329a5fd5a42" xlink:href="sncy-20221231.xsd#sncy_NonOperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_sncy_NonOperatingIncomeExpenseAbstract_bcf923a8-473f-4916-adf0-e329a5fd5a42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_245cf0c2-6ac2-4999-8a4c-9a6af31833ed" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromSubsidiariesNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_NonOperatingIncomeExpenseAbstract_bcf923a8-473f-4916-adf0-e329a5fd5a42" xlink:to="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_245cf0c2-6ac2-4999-8a4c-9a6af31833ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_e7c5b013-f80a-40c0-8ecb-4bf402282434" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_NonOperatingIncomeExpenseAbstract_bcf923a8-473f-4916-adf0-e329a5fd5a42" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_e7c5b013-f80a-40c0-8ecb-4bf402282434" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_78df5933-4023-4bee-8a29-c836f0905d64" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sncy_NonOperatingIncomeExpenseAbstract_bcf923a8-473f-4916-adf0-e329a5fd5a42" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_78df5933-4023-4bee-8a29-c836f0905d64" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_d61e986b-01fe-48da-8c0b-2f28e0e507b4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_d61e986b-01fe-48da-8c0b-2f28e0e507b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_eff8a78c-b2c2-42da-a3ed-a06d42717fd7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_eff8a78c-b2c2-42da-a3ed-a06d42717fd7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_067a2ba6-7911-442c-ad9c-d10b3a62a3d3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_us-gaap_NetIncomeLoss_067a2ba6-7911-442c-ad9c-d10b3a62a3d3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_afad1be5-7b36-4aa6-8522-8cc7b9db41e0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_afad1be5-7b36-4aa6-8522-8cc7b9db41e0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_2103290d-09eb-4949-8a95-5386556259f7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_2103290d-09eb-4949-8a95-5386556259f7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedIncomeStatementTable_a7575a6b-9127-485b-bb5f-a0fe960b2239" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CondensedIncomeStatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_6b89d245-de64-4158-9209-738a7eb298c4" xlink:to="loc_srt_CondensedIncomeStatementTable_a7575a6b-9127-485b-bb5f-a0fe960b2239" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_0323a73d-5cad-40d3-855a-ddcf1a90d9a6" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_CondensedIncomeStatementTable_a7575a6b-9127-485b-bb5f-a0fe960b2239" xlink:to="loc_srt_ConsolidatedEntitiesAxis_0323a73d-5cad-40d3-855a-ddcf1a90d9a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_0323a73d-5cad-40d3-855a-ddcf1a90d9a6_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_0323a73d-5cad-40d3-855a-ddcf1a90d9a6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_0323a73d-5cad-40d3-855a-ddcf1a90d9a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_e1bce651-1add-4198-aa03-8ffde06f3d28" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_0323a73d-5cad-40d3-855a-ddcf1a90d9a6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_e1bce651-1add-4198-aa03-8ffde06f3d28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_62071d7b-dfc4-4971-932b-06f681ea0cee" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_e1bce651-1add-4198-aa03-8ffde06f3d28" xlink:to="loc_srt_ParentCompanyMember_62071d7b-dfc4-4971-932b-06f681ea0cee" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
