noun
closing date; cut-off date; deadline
Business term for the date by which something must be submitted, an account is settled, or a period closes. Often used for payment deadlines, order cut-offs, or monthly accounting closures.
See also: 締め切り日
今月の締め日は25日です。
This month's closing date is the 25th.
請求書の締め日までにご入金ください。
Please make the payment by the invoice due date.
締め切り is a general deadline for submissions or applications, while 締め日 specifically refers to a recurring monthly or periodic closing date in business accounting or transactions.
Compound of 締め (shime, 'closing') + 日 (hi, 'day'), with rendaku voicing to び. The kanji 締 means 'tighten' or 'close', reflecting the sense of finalizing accounts or periods.