Lutidine \Lu"ti*dine\, n. [From toluidine, by transposition.] (Chem.) Any one of several metameric alkaloids, {C5H3N.(CH3)2}, of the pyridine series, obtained from bone oil as liquids, and having peculiar pungent odors. These alkaloids are also called respectively {dimethyl pyridine}, {ethyl pyridine}, etc.