Which term is used to describe the process of adding heat?

The term that describes the process of adding heat is "endothermic." This term specifically refers to reactions or processes that absorb heat from their surroundings. When a substance undergoes an endothermic reaction, it requires energy, often in the form of heat, to proceed, resulting in a decrease in temperature of the surroundings or environment.

In comparison, an exothermic process involves the release of heat, leading to an increase in the temperature of the surroundings. The word "thermal" generally pertains to heat-related concepts but does not specifically indicate a process of adding heat. "Calorific" relates to the heat content of substances but does not capture the active absorption of heat in a process. Hence, endothermic is the precise term used when heat is being absorbed during a reaction or process.