Thermodynamics is derived from two Greek words

  • Therme, which means heat
  • Dynamis, which means power

We know that 'thermodynamics' encapsulates many concepts like energy, temperature, entropy, exergy, heat, work, etc., then why give heat (therme) and Power (dynamis) such a special place?

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    $\begingroup$ From this web page: An article on the history of thermodynamics can do no worse than begin by citing the first usage of any version of the word thermodynamics. This was in an 1849 article by William Thomson referring to “thermo-dynamic engines”, by which he meant devices—in particular, steam engines—that convert heat (thermo) to motion (dynamics) $\endgroup$ Commented Jun 13, 2022 at 20:44
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    $\begingroup$ I think of "dynamics" as meaning motion. Compare: hydrostatics (about water standing still) and hydrodynamics (about water in motion). $\endgroup$ Commented Jun 14, 2022 at 0:32
  • $\begingroup$ @DaveLRenfro In the link that you gave (ncbi.nlm.nih.gov/pmc/articles/PMC7516509/…), under Friction, Fire, Phlogiston, Caloric section, they use the word heat. It seems like people used to use the word heat even before caloric theory,phlogiston theory, what did people mean by heat back then? before caloric theory, phlogiston theory were given? $\endgroup$ Commented Jun 15, 2022 at 11:55
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    $\begingroup$ what did people mean by heat back then --- This isn't my field, but since virtually everything that has ever been published in the 1700s and 1800s is freely available on the internet (it's quite a different matter regarding stuff from the past 100 years or so), this is something you can actually investigate yourself without the expense and time needed to travel to a major research library. See this google-books search, for instance. $\endgroup$ Commented Jun 15, 2022 at 13:32

1 Answer 1


Thermodynamics is indeed derived from the Greek words Therme (heat) and Dynamis (power). However, Dynamis is not the same as the Physics definition of Power but is synonymous with "might" or "strength".

The term "Thermodynamics" originates from the concept of "motive power of heat", which first appeared in 1849 in William Thomson's (Lord Kelvin) paper "An Account of Carnot's Theory of the Motive Power of Heat – with Numerical Results Deduced from Regnault's Experiments on Steam." The term is claimed to have been coined by James Joule in 1858 in reference to Thomson's paper.

Thus, Thermodynamics (or "thermo-dynamics" as written earlier) was associated with heat's motive power, that is, the "might" of heat to do work or cause motion.


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