cockpit locker vs locker

cockpit locker and locker both are nouns.

Word	Noun	Adjective	Verb	Adverb
cockpit locker	Yes	No	No	No
locker	Yes	No	No	No

As nouns, locker is a hypernym of cockpit locker; that is, locker is a word with a broader meaning than cockpit locker:

cockpit locker: (nautical) a large locker under the cockpit seating.
locker: a trunk for storing personal possessions; usually kept at the foot of a bed (as in a barracks)

Other hypernyms of cockpit locker include footlocker.

cockpit locker (noun)	locker (noun)
(nautical) a large locker under the cockpit seating.	a storage compartment for clothes and valuables; usually it has a lock
	a trunk for storing personal possessions; usually kept at the foot of a bed (as in a barracks)
	a fastener that locks or closes