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

Source: Webster's Revised Unabridged Dictionary (1913)
 

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: Webster's Revised Unabridged Dictionary (1913)