noun, noun or participle which takes 'suru'
A mechanical fastener for doors, gates, or lids. Also used as a suru-verb for the action of latching or locking into place.
ドアのラッチが壊れて閉まらない。
The door latch is broken and won't close.
カバーをラッチして固定する。
Latch the cover to secure it.
ロック (lock) is a more general term for locking mechanisms, while ラッチ specifically refers to a latch that holds something closed without necessarily requiring a key.
Borrowed from English 'latch'.