Source : Webster's Revised Unabridged Dictionary (1913)

Cereal \Ce"re*al\ n.
   Any grass cultivated for its edible grain, or the grain
   itself; -- usually in the plural.

Cereal \Ce"re*al\, a. [L. Cerealis pert. to Ceres, and hence, to
   agriculture. See {Ceres}.]
   Of or pertaining to the grasses which are cultivated for
   their edible seeds (as wheat, maize, rice, etc.), or to their
   seeds or grain.

Source : WordNet®

cereal
     adj : made of grain or relating to grain or the plants that
           produce it; "a cereal beverage"; "cereal grasses"

cereal
     n 1: grass whose starchy grains are used as food: wheat; rice;
          rye; oats; maize; buckwheat; millet [syn: {cereal grass}]
     2: foodstuff prepared from the starchy grains of cereal grasses
        [syn: {grain}, {food grain}]
     3: a breakfast food prepared from grain