Nitrile \Ni"trile\ (? or ?), n. [See Nitro-.]

(Chem.) Any one of a series of compounds bearing the cyanide radical (-CN); 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. [1913 Webster]

Note: The nitriles are named with reference to the acids produced by their decomposition, thus, hydrocyanic acid is formic nitrile, methyl cyanide is acetonitrile (also acetic nitrile), and ethyl cyanide is propionitrile (from propionic acid). [1913 Webster +PJC]

Source: The Collaborative International Dictionary of English v.0.48