niggling vs colloquialism

niggling is not a noun while colloquialism is a noun.

Word	Noun	Adjective	Verb	Adverb
niggling	No	Yes	No	No
colloquialism	Yes	No	No	No

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

niggling (adjective)	colloquialism (adjective)
(informal) small and of little importance