sundress vs frock

sundress and frock both are nouns.

Word	Noun	Adjective	Verb	Adverb
sundress	Yes	No	No	No
frock	Yes	No	Yes	No

As nouns, frock is a hypernym of sundress; that is, frock is a word with a broader meaning than sundress:

sundress: a light loose sleeveless summer dress with a wide neckline and thin shoulder straps that expose the arms and shoulders
frock: a one-piece garment for a woman; has skirt and bodice

Other hypernyms of sundress include dress.

sundress (noun)	frock (noun)
a light loose sleeveless summer dress with a wide neckline and thin shoulder straps that expose the arms and shoulders	a one-piece garment for a woman; has skirt and bodice
	a habit worn by clerics
	a long, loose outer garment

sundress (verb)	frock (verb)
	put a frock on