Source : Webster's Revised Unabridged Dictionary (1913)

Atropine \At"ro*pine\, n. [Gr. ? inflexible; hence ? ?, one of
   the three Parc[ae]; 'a priv. + ? to turn.] (Chem.)
   A poisonous, white, crystallizable alkaloid, extracted from
   the {Atropa belladonna}, or deadly nightshade, and the
   {Datura Stramonium}, or thorn apple. It is remarkable for its
   power in dilating the pupil of the eye. Called also
   {daturine}.

Source : WordNet®

atropine
     n : a poisonous crystalline alkaloid extracted from the
         nightshade family; used as an antispasmodic and to dilate
         the eye pupil; also administered in large amounts as an
         antidote for organophosphate nerve agents or
         organophosphate insecticides