·noun A powerful and very poisonous vegetable alkaloid found in the hemlock (Conium maculatum) and extracted as a colorless oil, C8H17N, of strong repulsive odor and acrid taste. It is regarded as a derivative of piperidine and likewise of one of the collidines. It occasions a gradual paralysis of the motor nerves. Called also coniine, coneine, conia, ·etc. ·see Conium, 2.