swimming costume vs garment

swimming costume and garment both are nouns.

Word	Noun	Adjective	Verb	Adverb
swimming costume	Yes	No	No	No
garment	Yes	No	Yes	No

As nouns, garment is a hypernym of swimming costume; that is, garment is a word with a broader meaning than swimming costume:

swimming costume (noun)	garment (noun)
tight fitting garment worn for swimming	an article of clothing

swimming costume (verb)	garment (verb)
	provide with clothes or put clothes on