at least vs colloquialism

at least is not a noun while colloquialism is a noun.

Word	Noun	Adjective	Verb	Adverb
at least	No	No	No	Yes
colloquialism	Yes	No	No	No

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

at least (adverb)	colloquialism (adverb)
not less than
if nothing else (`leastwise' is informal and `leastways' is colloquial)