Nitrile \Ni"trile\ (? or ?), n. [See {Nitro-}.] (Chem.) Any one of a series of cyanogen compounds; particularly, one of those cyanides of alcohol radicals which, by boiling with acids or alkalies, produce a carboxyl acid, with the elimination of the nitrogen as ammonia. Note: The nitriles are named with reference to the acids produced by their decomposition, thus, hydrocyanic acid is {formic nitrile}, and methyl cyanide is {acetic nitrile}.