endothermicPronunciation: /ˌɛndəʊˈθəːmɪk/Definition of endothermic adjective 1 Chemistry (of a reaction or process) accompanied by or requiring the absorption of heat. The opposite of exothermic. (of a compound) requiring a net input of heat for its formation from its constituent elements. 2 Zoology (of an animal) dependent on or capable of the internal generation of heat. Derivatives endothermal adjective endothermic in other Oxford dictionaries Definition of endothermic in the US English dictionary