colloquialism vs at least

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

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

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

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