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[ek-soh-thur-mik] /ˌɛk soʊˈθɜr mɪk/
adjective, Chemistry
noting or pertaining to a chemical change that is accompanied by a liberation of heat (opposed to endothermic).
Origin of exothermic
1880-85; exo- + thermic
Related forms
exothermically, exothermally, adverb
[ek-soh-ther-mis-i-tee] /ˌɛk soʊ θərˈmɪs ɪ ti/ (Show IPA),
noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for exothermic
  • When water is formed by burning hydrogen, that's an exothermic reaction.
  • Highly exothermic chemical reactions are needed to thrust spacecraft into the air.
  • Since this reaction is exothermic--that is, it releases heat--it requires no input of energy to drive it.
  • What is the difference between an endo and exothermic reaction.
  • Electron affinity is exothermic because energy is released when the nucleus attracts an electron.
  • The temperature increase that you record for an exothermic reaction is in the surroundings.
  • The exothermic welds and high compression fittings shall be listed for the purpose.
  • Contact of acids with water can be highly exothermic and can result in splatter and generation of mists.
British Dictionary definitions for exothermic


(of a chemical reaction or compound) occurring or formed with the evolution of heat Compare endothermic, exoergic
Derived Forms
exothermically, exothermally, adverb
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
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Word Origin and History for exothermic

1879, from French exothermique (1879), from exo- + thermique, ultimately from Greek therme "heat" (see thermal).

Online Etymology Dictionary, © 2010 Douglas Harper
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exothermic in Medicine

exothermic ex·o·ther·mic (ěk'sō-thûr'mĭk) or ex·o·ther·mal (-məl)

  1. Of or relating to a chemical reaction during which heat is released.

  2. Of of relating to the external warmth of the body.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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exothermic in Science
Relating to a chemical reaction that releases heat. Compare endothermic.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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