The Collaborative International Dictionary of English v.0.48:

Jimson weed \Jim"son weed`\
   See Jamestown weed. [Local, U.S.] Jin

WordNet (r) 3.0 (2006):

jimson weed
    n 1: intensely poisonous tall coarse annual tropical weed having
         rank-smelling foliage, large white or violet trumpet-shaped
         flowers and prickly fruits [syn: jimsonweed, jimson
         weed, Jamestown weed, common thorn apple, apple of
         Peru, Datura stramonium]