n. [ From Gr. &unr_; fire. ] (Physiol. Chem.) A nitrogenous base, C5H5N, obtained from the distillation of bone oil or coal tar, and by the decomposition of certain alkaloids, as a colorless liquid with a peculiar pungent odor. It is the nucleus of a large number of organic substances, among which several vegetable alkaloids, as nicotine and certain of the ptomaïnes, may be mentioned. See Lutidine. [ 1913 Webster ]