Meaning of “lock” - Learner’s Dictionary

lock

noun [ C ] us uk /lɒk/
Extra Examples
They had to force the lock.He changed the front door lock.She put the key in the lock and turned it.After the house was burgled she had all the locks changed.The lock was very stiff.
IN DOOR

B1 the thing that is used to close a door, window, etc, and that needs a key to open it:

I heard someone turn a key in the lock.
safety locks
WATER

a place on a river with gates to allow boats to move to a different water level

(Definition of “lock noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)