indole

 A white, crystalline substance, C8H7N, obtained from blue indigo, and almost all indigo derivatives, by a process of reduction; chemically, it is 2,3-benzopyrrole, a bicyclic heterocyclic compound, having a benzene ring fused to a pyrrole ring. It is also formed from proteinaceous matter, together with skatol, by putrefaction, and by fusion with caustic potash, and is present in human excrement, as well as in the intestinal canal of some herbivora. It is produced in rich growth media by the intestinal bacterium Escherichia coli.  [1913 Webster]