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.