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[en-thal-pee, en-thal-] /ˈɛn θæl pi, ɛnˈθæl-/
noun, plural enthalpies. Thermodynamics.
a quantity associated with a thermodynamic system, expressed as the internal energy of a system plus the product of the pressure and volume of the system, having the property that during an isobaric process, the change in the quantity is equal to the heat transferred during the process. Symbol: H.
Also called heat content, total heat.
Origin of enthalpy
1925-30; < Greek enthálp(ein) to warm in (en- en-2 + thálpein to warm) + -y3 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for enthalpy


/ˈɛnθəlpɪ; ɛnˈθæl-/
a thermodynamic property of a system equal to the sum of its internal energy and the product of its pressure and volume H Also called heat content, total heat
Word Origin
C20: from Greek enthalpein to warm in, from en-² + thalpein to warm
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 enthalpy

1927, from Greek enthalpein "to warm in," from en "in" (see en- (2)) + thalpein "to heat."

Online Etymology Dictionary, © 2010 Douglas Harper
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enthalpy in Medicine

enthalpy en·thal·py (ěn'thāl'pē, ěn-thāl'-)
A thermodynamic function of a system, equivalent to the sum of the internal energy of the system plus the product of its volume multiplied by the pressure exerted on it by its surroundings.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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enthalpy in Science
A partial measure of the internal energy of a system. Enthalpy cannot be directly measured, but changes in it can be. If an outside pressure on a system is held constant, a change in enthalpy entails a change in the system's internal energy, plus a change in the system's volume (meaning the system exchanges energy with the outside world). For example, in endothermic chemical reactions, the change in enthalpy is the amount of energy absorbed by the reaction; in exothermic reactions, it is the amount given off. See also thermodynamics.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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