colloquialism vs sure enough

colloquialism is a noun but sure enough is not a noun.

Word	Noun	Adjective	Verb	Adverb
colloquialism	Yes	No	No	No
sure enough	No	No	No	Yes

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

colloquialism (adverb)	sure enough (adverb)
	as supposed or expected
	definitely or positively (`sure' is sometimes used informally for `surely')