Caltha palustris vs kingcup

Caltha palustris and kingcup both are nouns.

Word	Noun	Adjective	Verb	Adverb
Caltha palustris	Yes	No	No	No
kingcup	Yes	No	No	No

As nouns, Caltha palustris and kingcup are synonyms defined as:

Caltha palustris and kingcup: swamp plant of Europe and North America having bright yellow flowers resembling buttercups

Other synonyms of Caltha palustris include cowslip, marsh marigold, May blob, meadow bright, water dragon.

Caltha palustris (noun)	kingcup (noun)
swamp plant of Europe and North America having bright yellow flowers resembling buttercups	any of various plants of the genus Ranunculus
	swamp plant of Europe and North America having bright yellow flowers resembling buttercups