1. Also endothermic. designating or pertaining to animals, as mammals and birds, whose blood ranges in temperatures from about 98° to 112°F (37° to 44°C) and remains relatively constant, irrespective of the temperature of the surrounding medium; homoiothermal.
  2. ardent, impetuous, or passionate: young and warm-blooded valor.

Origin of warm-blooded

First recorded in 1785–95
Related formswarm-blood·ed·ness, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for warm-blooded


  1. ardent, impetuous, or passionate
  2. (of birds and mammals) having a constant body temperature, usually higher than the temperature of the surroundingsTechnical name: homoiothermic
Derived Formswarm-bloodedness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

warm-blooded in Medicine


  1. Maintaining a relatively constant and warm body temperature independent of environmental temperature; homeothermic.
Related formswarm-blooded•ness n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

warm-blooded in Science


  1. Having a relatively warm body temperature that stays about the same regardless of changes in the temperature of the surroundings. Birds and mammals are warm-blooded.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.