buttercup vs butter-flower

buttercup and butter-flower both are nouns.

Word	Noun	Adjective	Verb	Adverb
buttercup	Yes	No	No	No
butter-flower	Yes	No	No	No

As nouns, buttercup and butter-flower are synonyms defined as:

buttercup and butter-flower: any of various plants of the genus Ranunculus

Other synonyms of buttercup include butterflower, crowfoot, goldcup, kingcup.

buttercup (noun)	butter-flower (noun)
any of various plants of the genus Ranunculus	any of various plants of the genus Ranunculus