A very poisonous alkaloid resembling brucine, obtained
   from various species of plants, especially from species of Loganiaceae,
   as from the seeds of the St. Ignatius bean (Strychnos Ignatia) and from
   nux vomica. It is obtained as a white crystalline substance, having a
   very bitter acrid taste, and is employed in medicine (chiefly in the
   form of the sulphate) as a powerful neurotic stimulant. Called also
   strychnia, and formerly strychnina.