c. 1400, from un- (2) "reverse, opposite of" + lock (v.). Figurative sense is attested from 1530s. Old English had unlucan "to unlock, open." Related: Unlocked; unlocking.
unlock the door
The door unlocked from the inside
unlimited
unlink
unlisted
unlivable
unload
unlock
unlooked
unloose
unloved
unlovely
unlucky
