colloquialism vs at any rate

colloquialism is a noun but at any rate is not a noun.

Word	Noun	Adjective	Verb	Adverb
colloquialism	Yes	No	No	No
at any rate	No	No	No	Yes

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

colloquialism (adverb)	at any rate (adverb)
	used to indicate that a statement explains or supports a previous statement
	if nothing else (`leastwise' is informal and `leastways' is colloquial)