noun
end date; closing date
Refers to the date on which something finishes, such as a contract, event, or application period.
キャンペーンの終了日は来月の15日です。
The campaign end date is the 15th of next month.
契約の終了日を確認してください。
Please check the contract end date.
締切日 is a deadline for submission, while 終了日 is the date something ends.
Compound of 終了 (shūryō, 'end, completion') and 日 (bi, 'day').