self-locking
adjectiveUK /ˌself ˈlɒkɪŋ/
US /ˌself ˈlɑːkɪŋ/
Something self-locking locks by itself when you close it.
The gate has a self-locking latch, so it shuts tight on its own.
RELATED WORDS
OTHER MEANINGS
2. A nut or bolt that stays tight by itself and does not loosen from shaking.
Use a self-locking nut so the wheel does not come loose.
3. A door or gate that locks automatically when it closes.
The self-locking door kept the shed safe.
4. A device that holds itself in place without extra help.
The self-locking buckle clicked shut.