define endothermic and exothermic reactions
Diffen âº Science âº Chemistry. An endothermic reaction occurs when energy is absorbed from the surroundings in the form of heat. Conversely, an exothermic reaction is one in which energy is released from the system into the surroundings. The terms are commonly used in the physical sciences and chemistry.
Noun. 1. endothermic reaction-a chemical reaction accompanied by the absorption of heat. chemical reaction, reaction - (chemistry) a process in which one or more substances are changed into others; there was a chemical reaction of the lime with the ground water.