colloquialism vs insignificant

colloquialism is a noun but insignificant is not a noun.

Word	Noun	Adjective	Verb	Adverb
colloquialism	Yes	No	No	No
insignificant	No	Yes	No	No

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

colloquialism (adjective)	insignificant (adjective)
	devoid of importance, meaning, or force
	signifying nothing
	of little importance or influence or power; of minor status
	small and unimpressive