nitrile /ˈnaɪtɹaɪl/ noun2 •Any of a class of organic compounds containing a cyano functional group −C≡N; they are named as derivatives of the appropriate carboxylic acid. •A type of synthetic rubber formed by the copolymerization of acrylonitrile and butadiene: nitrile rubber.Sitting in a box under my bed are the nitrile gloves that I bought to practise with my forensic kit. — 2021 formsnitriles