The American Heritage® Dictionary of the English Language, 4th Edition
n. An organism, such as a mammal or bird, having a body temperature that is constant and largely independent of the temperature of its surroundings; an endotherm.
n. A creature that maintains a stable internal body temperature regardless of external influence.
the GNU version of the Collaborative International Dictionary of English
n. A homoiothermal animal.
The Century Dictionary and Cyclopedia
n. An animal with a bodily temperature which is nearly constant and independent of, and usually higher than, that of the surrounding medium; a warm-blooded animal.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. an animal that has a body temperature that is relatively constant and independent of the environmental temperature
Word Usage
"Man is a "homeotherm" -- that is, our bodies try to maintain a constant body temperature irrespective of the temperature of their surroundings."