%pyrrole%

n. [ Gr. &unr_; flame-colored (from &unr_; 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 ]