Meaning

noun grass whose starchy grains are used as food: wheat; rice; rye; oats; maize; buckwheat; millet

noun foodstuff prepared from the starchy grains of cereal grasses

noun a breakfast food prepared from grain

originBorrowed from French céréale (“having to do with cereal”), from Latin Cerealis (“of or relating to Ceres”), from Ceres (“Roman goddess of agriculture”), from Proto-Indo-European *ḱer- (“grow”), from which also Latin sincerus (English sincere) and Latin crēscō (“grow”) (English crescent). The adjective is equivalent to Cere(s) + -al.

Etymology from Wiktionary, CC BY-SA 3.0