pyrrol \pyr"rol\, pyrrole \pyr"role\, n. [Gr. ? flame-colored
   (from ? fire) + L. oleum oil.] (Chem.)
   A nitrogenous heterocyclic base found in coal tar, bone oil,
   and other distillates of organic substances, and also
   produced synthetically as a colorless liquid, C4H5N, having
   on odor like that of chloroform. It is the nucleus and origin
   of a large number of derivatives. So called because it colors
   a splinter of wood moistened with hydrochloric acid a deep
   red.
   [1913 Webster]