Which term best describes an animal that, although generating a significant amount of heat through metabolism, nonetheless does not maintain a constant body temperature

Heterothermic endotherm

Explanation:

Heterothermic endotherms are those organisms whose internal heat level shifts, however the vast majority of its warmth is delivered by its own tissues.   Endothermy: Endothermy is the system where through intern production body acquires heat. The heat is generated through metabolic system, possessed by Endotherm organisms. To produce heat is vigorously expensive, which implies that these organisms have high lively and wholesome necessities.   Heterothermy: Heterothermy happens in organisms which can change from endothermy to ectothermy. This normally occurs in little winged organisms and warm blooded organisms with high metabolic rates (very dynamic and with high lively prerequisites), which decline their internal heat level during idleness periods. These latency periods for the most part are yearly or day by day.