The Collaborative International Dictionary of English v.0.48:

Solanum \So*la"num\, prop. n. [L., nightshade.] (Bot.)
   A genus of plants comprehending the potato (Solanum
   tuberosum), the eggplant (Solanum melongena, and several
   hundred other species; nightshade.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mad-apple \Mad"-ap`ple\, Mad apple \Mad" ap`ple\, n.
   1. (Bot.) The eggplant bush (Solanum melongena). See
      Eggplant.

   Syn: eggplant, aubergine, brinjal, eggplant bush, garden egg,
        Solanum melongena.
        [1913 Webster + WordNet 1.5]

   2. The fruit of the eggplant bush, a large egg-shaped
      vegetable having a shiny skin typically dark purple but
      occasionally white or yellow.

   Syn: eggplant, aubergine.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

eggplant \egg"plant`\, egg-plant \egg-plant\, n.
   1. (Bot.) A plant (Solanum Melongena), of East Indian
      origin, allied to the tomato, and bearing a large, glossy,
      edible fruit, shaped somewhat like an egg; mad-apple. It
      is widely cultivated for its fruit, commonly eaten as a
      vegetable.

   Syn: eggplant, aubergine, brinjal, eggplant bush, garden egg,
        mad apple, Solanum melongena.
        [1913 Webster + WordNet 1.5]

   2. The fruit of the eggplant[1].
      [PJC]

WordNet (r) 3.0 (2006):

Solanum melongena
    n 1: hairy upright herb native to southeastern Asia but widely
         cultivated for its large glossy edible fruit commonly used
         as a vegetable [syn: eggplant, aubergine, brinjal,
         eggplant bush, garden egg, mad apple, Solanum
         melongena]