It is the ability of an organism.In biology, an organism is any living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homeostasis as a stable whole...to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. This process is one aspect of homeostasis,Homeostasis is the property of a system, either open or closed, that regulates its internal environment and tends to maintain a stable, constant condition...
: a dynamic state of stability between an animal's internal environment and its external environment. I hoped that helped. :)