ho·me·o·therm (h??m?-?-thûrm?) also ho·moi·o·therm (h?-moi??-)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.ho?me·o·ther?mi·a (-thûr?m?-?), ho?me·o·ther?my (-thûr?m?) n.ho?me·o·ther?mic (-m?k) adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.homeotherm , homoeotherm or homoiothermn (Zoology) zoology an animal or organism that keeps its body at an almost constant temperatureCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014