1To close; to be shut (of a door, window, shop, etc.); to go from open to closed. An intransitive verb, usually written 閉まる.
デパートは夜九時に閉まります。
The department store closes at nine at night.
風で玄関のドアがバタンと閉まった。
The front door slammed shut in the wind.
シャッターが閉まっていて、店の中の様子が見えない。
The shutter is down, so I can't see inside the shop.
ふたがきちんと閉まらないと、中身がこぼれてしまう。
If the lid doesn't close properly, the contents will spill.
2To become firm, toned, or well-knit (of the body, face, or expression); to look tightened and fit. Written 締まる.
毎日走っているうちに、お腹まわりが締まってきた。
After running every day, my waistline has gotten firmer.
試合を前に、選手たちの顔つきが締まってきた。
With the match approaching, the players' faces have taken on a focused, determined look.
トレーニングの効果で、体がすっかり締まった。
Thanks to the training, my body has become really toned.
3To be locked; to become secured so that it cannot be opened. Written 閉まる.
帰宅したらドアが閉まっていて鍵もかかっていた。
When I got home the door was shut and locked.
金庫がしっかり閉まっているか、もう一度確認した。
I checked once more that the safe was securely locked.
4To be tightened or drawn tight (of a screw, bolt, belt, etc.); to become firmly fastened. Written 締まる.
ボルトがしっかり締まっていないと事故につながる。
If the bolts aren't tightened firmly, it can lead to an accident.
ベルトがきつく締まって、お腹が苦しい。
The belt is fastened too tight and my stomach feels uncomfortable.
5To become tense, focused, or disciplined (of one's mind or the mood of a place); also, to sober up. A figurative use, written 締まる.
監督の一言で、チームの雰囲気がぐっと締まった。
With one word from the coach, the team's atmosphere tightened up sharply.
大事な発表を前に、気持ちが締まった。
Before the important presentation, I felt myself tense up and focus.