The Collaborative International Dictionary of English v.0.48:

Indian corn \Indian corn\ (Bot.),
   A cereal plant of the genus Zea (Zea Mays), also simply
   called corn, used widely as a food; the maize, a native
   plant of America; more specifically: a primitive variety of
   Zea Mays having variegated kernels on each cob, in
   distinction from the more commonly used yellow corn; it is
   often used as decoration at Thanksgiving time. See Corn,
   and Maize.
   [1913 Webster +PJC]

   Note: In modern American usage, the word corn when unmodified
         usually refers to yellow corn, and Indian corn refers
         to the variegated variety.
         [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Corn \Corn\, n. [AS. corn; akin to OS. korn, D. koren, G., Dan.,
   Sw., & Icel. korn, Goth. ka['u]rn, L. granum, Russ. zerno.
   Cf. Grain, Kernel.]
   1. A single seed of certain plants, as wheat, rye, barley,
      and maize; a grain.
      [1913 Webster]

   2. The various farinaceous grains of the cereal grasses used
      for food, as wheat, rye, barley, maize, oats.
      [1913 Webster]

   Note: In Scotland, corn is generally restricted to oats, in
         the United States, to maize, or Indian corn (see
         sense 3), and in England to wheat.
         [1913 Webster +PJC]

   3. a tall cereal plant (Zea mays) bearing its seeds as
      large kernels in multiple rows on the surface of a hard
      cylindrical ear, the core of which (the cob) is not
      edible; -- also called Indian corn and, in technical
      literature, maize. There are several kinds; as, yellow
      corn, which grows chiefly in the Northern States, and is
      yellow when ripe; white corn or southern corn, which
      grows to a great height, and has long white kernels;
      sweet corn, comprising a number of sweet and tender
      varieties, grown chiefly at the North, some of which have
      kernels that wrinkle when ripe and dry; pop corn, any
      small variety, used for popping. Corn seeds may be cooked
      while on the ear and eaten directly, or may be stripped
      from the ear and cooked subsequently. The term Indian
      corn is often used to refer to a primitive type of corn
      having kernels of varied color borne on the same cob; it
      is used for decoration, especially in the fall.
      [1913 Webster +PJC]

   4. The plants which produce corn, when growing in the field;
      the stalks and ears, or the stalks, ears, and seeds, after
      reaping and before thrashing.
      [1913 Webster]

            In one night, ere glimpse of morn,
            His shadowy flail had thrashed the corn. --Milton.
      [1913 Webster]

   5. A small, hard particle; a grain. "Corn of sand." --Bp.
      Hall. "A corn of powder." --Beau. & Fl.
      [1913 Webster]

   Corn ball, a ball of popped corn stuck together with soft
      candy from molasses or sugar.

   Corn bread, bread made of Indian meal.

   Corn cake, a kind of corn bread; johnny cake; hoecake.

   Corn cockle (Bot.), a weed (Agrostemma Githago syn.
      Lychnis Githago), having bright flowers, common in grain
      fields.

   Corn flag (Bot.), a plant of the genus Gladiolus; --
      called also sword lily.

   Corn fly. (Zool.)
      (a) A small fly which, in the larval state, is injurious
          to grain, living in the stalk, and causing the disease
          called "gout," on account of the swelled joints. The
          common European species is Chlorops t[ae]niopus.
      (b) A small fly (Anthomyia ze) whose larva or maggot
          destroys seed corn after it has been planted.

   Corn fritter, a fritter having green Indian corn mixed
      through its batter. [U. S.]

   Corn laws, laws regulating trade in corn, especially those
      in force in Great Britain till 1846, prohibiting the
      importation of foreign grain for home consumption, except
      when the price rose above a certain rate.

   Corn marigold. (Bot.) See under Marigold.

   Corn oyster, a fritter containing grated green Indian corn
      and butter, the combined taste resembling that of oysters.
      [U.S.]

   Corn parsley (Bot.), a plant of the parsley genus
      (Petroselinum segetum), a weed in parts of Europe and
      Asia.

   Corn popper, a utensil used in popping corn.

   Corn poppy (Bot.), the red poppy (Papaver Rh[oe]as),
      common in European cornfields; -- also called corn rose.


   Corn rent, rent paid in corn.

   Corn rose. See Corn poppy.

   Corn salad (Bot.), a name given to several species of
      Valerianella, annual herbs sometimes used for salad.
      Valerianella olitoria is also called lamb's lettuce.


   Corn stone, red limestone. [Prov. Eng.]

   Corn violet (Bot.), a species of Campanula.

   Corn weevil. (Zool.)
      (a) A small weevil which causes great injury to grain.
      (b) In America, a weevil (Sphenophorus ze[ae]) which
          attacks the stalk of maize near the root, often doing
          great damage. See Grain weevil, under Weevil.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Indian corn
    n 1: tall annual cereal grass bearing kernels on large ears:
         widely cultivated in America in many varieties; the
         principal cereal in Mexico and Central and South America
         since pre-Columbian times [syn: corn, maize, Indian
         corn, Zea mays]