colloquialism vs fresh fish

colloquialism and fresh fish both are nouns.

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

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