romper vs garment

romper and garment both are nouns.

Word	Noun	Adjective	Verb	Adverb
romper	Yes	No	No	No
garment	Yes	No	Yes	No

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

romper: a one-piece garment for children to wear at play; the lower part is shaped like bloomers
garment: an article of clothing

romper (noun)	garment (noun)
a one-piece garment for children to wear at play; the lower part is shaped like bloomers	an article of clothing
a person who romps or frolics

romper (verb)	garment (verb)
	provide with clothes or put clothes on