The Collaborative International Dictionary of English v.0.48:

Potato \Po*ta"to\, n.; pl. Potatoes. [Sp. patata potato,
   batata sweet potato, from the native American name (probably
   batata) in Hayti.] (Bot.)
      (a) A plant (Solanum tuberosum) of the Nightshade
          family, and its esculent farinaceous tuber, of which
          there are numerous varieties used for food. It is
          native of South America, but a form of the species is
          found native as far north as New Mexico.
      (b) The sweet potato (see below).
          [1913 Webster]

   Potato beetle, Potato bug. (Zool.)
      (a) A beetle (Doryphora decemlineata) which feeds, both
          in the larval and adult stages, upon the leaves of the
          potato, often doing great damage. Called also
          Colorado potato beetle, and Doryphora. See
          Colorado beetle.
      (b) The Lema trilineata, a smaller and more slender
          striped beetle which feeds upon the potato plant, bur
          does less injury than the preceding species.

   Potato fly (Zool.), any one of several species of blister
      beetles infesting the potato vine. The black species
      (Lytta atrata), the striped (Lytta vittata), and the
      gray (Lytta Fabricii syn. Lytta cinerea) are the most
      common. See Blister beetle, under Blister.

   Potato rot, a disease of the tubers of the potato, supposed
      to be caused by a kind of mold (Peronospora infestans),
      which is first seen upon the leaves and stems.

   Potato weevil (Zool.), an American weevil (Baridius
      trinotatus) whose larva lives in and kills the stalks of
      potato vines, often causing serious damage to the crop.

   Potato whisky, a strong, fiery liquor, having a hot, smoky
      taste, and rich in amyl alcohol (fusel oil); it is made
      from potatoes or potato starch.

   Potato worm (Zool.), the large green larva of a sphinx, or
      hawk moth (Macrosila quinquemaculata); -- called also
      tomato worm. See Illust. under Tomato.

   Seaside potato (Bot.), Ipom[oe]a Pes-Capr[ae], a kind of
      morning-glory with rounded and emarginate or bilobed
      leaves. [West Indies]

   Sweet potato (Bot.), a climbing plant (Ipom[oe]a Balatas)
      allied to the morning-glory. Its farinaceous tubers have a
      sweetish taste, and are used, when cooked, for food. It is
      probably a native of Brazil, but is cultivated extensively
      in the warmer parts of every continent, and even as far
      north as New Jersey. The name potato was applied to this
      plant before it was to the Solanum tuberosum, and this
      is the "potato" of the Southern United States.

   Wild potato. (Bot.)
      (a) A vine (Ipom[oe]a pandurata) having a pale purplish
          flower and an enormous root. It is common in sandy
          places in the United States.
      (b) A similar tropical American plant (Ipom[oe]a
          fastigiata) which it is thought may have been the
          original stock of the sweet potato.
          [1913 Webster]

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):

potato worm
    n 1: large green white-striped hawkmoth larva that feeds on
         tomato and potato plants; similar to tobacco hornworm [syn:
         tomato hornworm, potato worm, Manduca
         quinquemaculata]