a flammable, colorless or pale-yellow liquid base, CHN, having a sharp, penetrating odor: it is produced in the distillation of coal tar or bone oil and is used in the synthesis of vitamins and drugs, as a solvent, etc.
See pyridine in American Heritage Dictionary 4
(pĭrˈĭ-dēnˌ)
noun
A flammable, colorless or yellowish liquid base, C5H5N, having a penetrating odor and serving as the parent compound of many biologically important derivatives. It is used as a solvent and waterproofing agent and in the manufacture of various drugs and vitamins.