noun A type of storage compartment with a lock, usually used to store personal possessions for public use, such as in schools, railway stations, place of work, gyms, sports centers.
The student placed her books in her locker when she arrived at school.
noun A lockable cubicle.
She was afraid to come out of the locker.
noun A storage compartment on a ship, not necessarily one that can be locked.
noun One who locks something.
The locker of the trapped chest must be careful, so as not to spring the trap.