fresh fish vs colloquialism

fresh fish and colloquialism both are nouns.

Word	Noun	Adjective	Verb	Adverb
fresh fish	Yes	No	No	No
colloquialism	Yes	No	No	No

fresh fish (noun)	colloquialism (noun)
soldiers who are regarded as expendable in the face of artillery fire	a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech