colloquialism vs foolish

colloquialism is a noun but foolish is not a noun.

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

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

colloquialism (adjective)	foolish (adjective)
	devoid of good sense or judgment
	having or revealing stupidity