closet vs broom closet

closet and broom closet both are nouns.

Word	Noun	Adjective	Verb	Adverb
closet	Yes	No	Yes	No
broom closet	Yes	No	No	No

As nouns, broom closet is a hyponym of closet; that is, broom closet is a word with a more specific, narrower meaning than closet:

Other hyponyms of closet include airing cupboard, safe, supply closet.

closet (noun)	broom closet (noun)
a small private room for study or prayer	a small room for storing brooms and other cleaning equipment
a toilet in Britain
a tall piece of furniture that provides storage space for clothes; has a door and rails or hooks for hanging clothes
a small room (or recess) or cabinet used for storage space

closet (verb)	broom closet (verb)
confine to a small space, as for intensive work