Answer: endothermic

AnswerCrossword Clue
endothermic(of an animal) Dependent on or capable of the internal generation of heat
endothermic(of a reaction or process) Accompanied by or requiring the absorption of heat
endothermiccharacterized by or formed with absorption of heat also ENDOTHERMAL
endothermic(of a compound) Requiring a net input of heat for its formation from its constituent elements