The Collaborative International Dictionary of English v.0.48:

Strychnine \Strych"nine\, n. [L. strychnos a kind of nightshade,
   Gr. ?: cf. F. strychnine.] (Chem.)
   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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

strychnine
    n 1: an alkaloid plant toxin extracted chiefly from nux vomica;
         formerly used as a stimulant