romper vs romper suit

romper and romper suit both are nouns.

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

As nouns, romper and romper suit are synonyms defined as:

romper and romper suit: a one-piece garment for children to wear at play; the lower part is shaped like bloomers

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