colloquialism vs yellow-bellied

colloquialism is a noun but yellow-bellied is not a noun.

Word	Noun	Adjective	Verb	Adverb
colloquialism	Yes	No	No	No
yellow-bellied	No	Yes	No	No

colloquialism (noun)	yellow-bellied (noun)
a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech

colloquialism (adjective)	yellow-bellied (adjective)
	easily frightened