Source : Webster's Revised Unabridged Dictionary (1913)

Hyoscyamine \Hy`os*cy"a*mine\, n. [See {Hyoscyamus}.] (Chem.)
   An alkaloid found in henbane ({Hyoscyamus niger}), and
   regarded as its active principle. It is also found with other
   alkaloids in the thorn apple and deadly nightshade. It is
   extracted as a white crystalline substance, with a sharp,
   offensive taste. Hyoscyamine is isomeric with atropine, is
   very poisonous, and is used as a medicine for neuralgia, like
   belladonna. Called also {hyoscyamia}, {duboisine}, etc.

Hyoscyamus \Hy`os*cy"a*mus\, n. [L., fr. Gr. ?; ? a sow, hog + ?
   a bean.]
   1. (Bot.) A genus of poisonous plants of the Nightshade
      family; henbane.

   2. (Med.) The leaves of the black henbane ({Hyoscyamus
      niger}), used in neuralgic and pectorial troubles.

Source : WordNet®

Hyoscyamus niger
     n : poisonous fetid Old World herb having sticky hairy leaves
         and yellow-brown flowers; yields hyoscyamine and
         scopolamine [syn: {henbane}, {black henbane}, {stinking
         nightshade}]