Cereal is a grassy grain used for food, like corn or wheat. But if someone offers you a bowl of cereal, don’t expect a pile of grass. Cereal is also a popular breakfast food served in a bowl with milk.
You can use the word cereal when you talk about a grain crop, the harvested grain, or the prepared breakfast food. Oatmeal is a hot cereal, and Cheerios is a cold one. Originally, cereal meant "having to do with edible grain," from the Latin Cerealis, "of grain," but also "of Ceres, the Roman goddess of agriculture." Next time you enjoy a bowl of Fruit Loops, make sure to thank Ceres, the goddess of agriculture.