The act or state of closing — a noun referring to something being closed properly, like a door or box.
ドアの閉まりが悪いので、冬は隙間風が入ってくる。
The door doesn't close properly, so drafts come in during winter.
箱の閉まりを確かめてから発送してください。
Please check that the box is properly closed before shipping.
キャップの閉まりが甘いと液体が漏れる恐れがある。
If the cap isn't tightly closed, the liquid may leak.