en·​thal·​py ˈen-ˌthal-pē How to pronounce enthalpy (audio) en-ˈthal- How to pronounce enthalpy (audio)
: the sum of the internal energy of a body or system and the product of its volume multiplied by the pressure

Examples of enthalpy in a Sentence

Recent Examples on the Web The project will test hypersonic reactions inside UCF’s unique hypersonic high-enthalpy reaction, or HyperREACT, facility which was in part created and designed by Rosato. Natalia Jaramillo, orlandosentinel.com, 1 Dec. 2021

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Word History


borrowed from Dutch enthalpie, from Greek enthálpein "to impart warmth" (from en- en- entry 2 + thálpein "to warm, heat," probably a syncopated form of the base seen in thalykrós "warm, glowing," of pre-Greek origin) + Dutch -ie -y entry 2

Note: The word was introduced in print by the Irish-born (later South African) mathematician and physicist John Patrick Dalton (1886-1965) in "Researches on the Joule-Kelvin effect, especially at low temperatures. I. Calculations for hydrogen," Koninklijke Akademie van Wetenschappen te Amsterdam, Proceedings of the Section of Sciences, vol. 11, 2nd part (July, 1909), p. 864. This paper was published as a translation of the Dutch original, "Onderzoekingen over het Joule-Kelvin-effect in het bijzonder bij lage temperaturen. I. Berekeningen voor waterstof," presented by the Dutch physicist Heike Kammerlingh Onnes (1853-1926) as a report to the March 27, 1909, meeting of the mathematics and physics division of the Royal Netherlands Academy of Sciences (Verslag van de gewone vergaderingen der Wis- en Natuurkundige Afdeeling, deel 17, 2de gedeelte [May, 1909], pp. 924-34). Dalton, a temporary researcher in Leiden, presumably wrote his paper in English, so that what is presented as an English translation is most likely the original, with the Dutch report being a translation by Onnes and/or the editors of the journal. On the first occurrence of the word enthalpy, Dalton mentions in a footnote that "this name has been suggested by Kamerlingh Onnes to indicate the function (ε + pv) —the 'Heat function' of Gibbs." Onnes himself does not appear to have used the word earlier, at least in publications (see Hendrick C. Van Ness, "H is for Enthalpy," letter to Journal of Chemical Education, vol. 80, no. 5 [May, 2003], p. 486).

First Known Use

1909, in the meaning defined above

Time Traveler
The first known use of enthalpy was in 1909

Dictionary Entries Near enthalpy

Cite this Entry

“Enthalpy.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/enthalpy. Accessed 23 Sep. 2023.

Medical Definition


en·​thal·​py ˈen-ˌthal-pē How to pronounce enthalpy (audio) en-ˈ How to pronounce enthalpy (audio)
plural enthalpies
: the sum of the internal energy of a body and the product of its volume multiplied by the pressure

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