A deadline or cut-off time; the final date/time for submissions or applications.
レポートの締め切りは来週の金曜日です。
The deadline for the report is next Friday.
申し込みの締め切りを過ぎると受付できません。
If you miss the application deadline, we cannot accept it.
締め切りが迫っていて、徹夜で作業した。
The deadline was approaching, so I worked overnight.
採用の応募締め切りは6月30日です。
The application deadline for recruitment is June 30.
The act of closing up (a door, window, etc.) so that a space is sealed off; the closed state.
台風が来るので窓を締め切っておいた。
Since a typhoon was coming, I shut all the windows.
店は夜になると入り口を締め切る。
The shop closes off its entrance at night.
会場は終日締め切られていた。
The venue was closed off for the entire day.
A cofferdam: a temporary structure used in construction to dam off water for work.
河川工事では締め切りをして仮排水路を作る。
In river construction they build a cofferdam and create a temporary diversion channel.