The Collaborative International Dictionary of English v.0.48:

Bittersweet \Bit"ter*sweet`\, n.
   1. Anything which is bittersweet.
      [1913 Webster]

   2. A kind of apple so called. --Gower.
      [1913 Webster]

   3. (Bot.)
      (a) A climbing shrub, with oval coral-red berries
          (Solanum dulcamara); woody nightshade. The whole
          plant is poisonous, and has a taste at first sweetish
          and then bitter. The branches are the officinal
          dulcamara.
      (b) An American woody climber (Celastrus scandens),
          whose yellow capsules open late in autumn, and
          disclose the red aril which covers the seeds; -- also
          called Roxbury waxwork.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dulcamara \Dul`ca*ma"ra\, n. [NL., fr. L. dulcis sweet + amarus
   bitter.] (Bot.)
   A plant (Solanum Dulcamara). See Bittersweet, n., 3
   (a) .
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dulcamarin \Dul`ca*ma"rin\, n. (Chem.)
   A glucoside extracted from the bittersweet (Solanum
   Dulcamara), as a yellow amorphous substance. It probably
   occasions the compound taste. See Bittersweet, 3
   (a) .
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Felonwort \Fel"on*wort`\, n. (Bot.)
   The bittersweet nightshade (Solanum Dulcamara). See
   Bittersweet.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Solanum dulcamara
    n 1: poisonous perennial Old World vine having violet flowers
         and oval coral-red berries; widespread weed in North
         America [syn: bittersweet, bittersweet nightshade,
         climbing nightshade, deadly nightshade, poisonous
         nightshade, woody nightshade, Solanum dulcamara]