heatheatheatsheatedheating2 (alsoheat up) verb (heats, heating, heated)to make something hot; to become hot: I heated some milk in a saucepan. Wait for the oven to heat up before you put the food in.heatheat1noun1(no plural) the feeling of something hot: the heat of the sun2(no plural) hot weather: I love the heat.oppositecold3(pluralheats) one of the first parts of a race or competition