step-in vs panty

step-in and panty both are nouns.

Word	Noun	Adjective	Verb	Adverb
step-in	Yes	No	No	No
panty	Yes	No	No	No

As nouns, step-in and panty are synonyms defined as:

Other synonyms of step-in include pantie, scanty.

step-in (noun)	panty (noun)
short underpants for women or children	short underpants for women or children