Nouns

(n)cereal, cereal grassgrass whose starchy grains are used as food: wheat; rice; rye; oats; maize; buckwheat; millet
(n)grain, food grain, cerealfoodstuff prepared from the starchy grains of cereal grasses
(n)cereala breakfast food prepared from grain

Adjectives

(a)cerealmade of grain or relating to grain or the plants that produce it“a cereal beverage”, “cereal grasses”