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 ptomaines, may be mentioned.
   See Lutidine.