The Collaborative International Dictionary of English v.0.48:

Tomato \To*ma"to\, n.; pl. Tomatoes. [Sp. or Pg. tomate, of
   American Indian origin; cf. Mexican tomail.] (Bot.)
   The fruit of a plant of the Nightshade family (Lycopersicum
   esculentun); also, the plant itself. The fruit, which is
   called also love apple, is usually of a rounded, flattened
   form, but often irregular in shape. It is of a bright red or
   yellow color, and is eaten either cooked or uncooked.
   [1913 Webster]

   Tomato gall (Zool.), a large gall consisting of a mass of
      irregular swellings on the stems and leaves of grapevines.
      They are yellowish green, somewhat tinged with red, and
      produced by the larva of a small two-winged fly
      (Lasioptera vitis).

   Tomato sphinx (Zool.), the adult or imago of the tomato
      worm. It closely resembles the tobacco hawk moth. Called
      also tomato hawk moth. See Illust. of Hawk moth.

   Tomato worm (Zool.), the larva of a large hawk moth
      (Manduca quinquemaculata, Protoparce quinquemaculata,
      Sphinx quinquemaculata, or Macrosila quinquemaculata)
      which feeds upon the leaves of the tomato and potato
      plants, often doing considerable damage. Called also
      tomato hornworm and potato worm, and in the Southern
      U. S. tobacco fly.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

tomato
    n 1: mildly acid red or yellow pulpy fruit eaten as a vegetable
    2: native to South America; widely cultivated in many varieties
       [syn: tomato, love apple, tomato plant, Lycopersicon
       esculentum]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "tomato":
   Irish potato, Jane, Kraut, aubergine, babe, baby, bawd, beans,
   biddy, bird, bitch, broad, cabbage, call girl, chick, colleen,
   cutie, dame, damoiselle, damsel, demoiselle, doll, drab, eggplant,
   fille, filly, frail, gal, girl, girlie, greens, heifer, hen,
   hoyden, jeune fille, jill, junior miss, lass, lassie, legumes,
   little missy, love apple, mad apple, mademoiselle, maid, maiden,
   minx, miss, missy, nymphet, piece, pieplant, potato, potherbs,
   poule, produce, rhubarb, romp, schoolgirl, schoolmaid, schoolmiss,
   skirt, slip, spud, subdeb, subdebutante, subteen, subteener, tater,
   teenybopper, tomboy, vegetables, virgin, wench, white potato,
   young creature, young thing