from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. For a closed thermodynamic system, a quantitative measure of the amount of thermal energy not available to do work.
  • n. A measure of the disorder or randomness in a closed system.
  • n. A measure of the loss of information in a transmitted message.
  • n. The tendency for all matter and energy in the universe to evolve toward a state of inert uniformity.
  • n. Inevitable and steady deterioration of a system or society.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A measure of the amount of information and noise present in a signal. Originally a tongue in cheek coinage, has fallen into disuse to avoid confusion with thermodynamic entropy.
  • n. The tendency of a system that is left to itself to descend into chaos.

from the GNU version of the Collaborative International Dictionary of English

  • n. A certain property of a body, expressed as a measurable quantity, such that when there is no communication of heat the quantity remains constant, but when heat enters or leaves the body the quantity increases or diminishes. If a small amount, h, of heat enters the body when its temperature is t in the thermodynamic scale the entropy of the body is increased by h ÷ t. The entropy is regarded as measured from some standard temperature and pressure. Sometimes called the thermodynamic function.

from The Century Dictionary and Cyclopedia

  • n. In physics: As used by Clausius, the inventor of the word, and others, that part of the energy of a system which cannot be converted into mechanical work without communication of heat to some other body, or change of volume.
  • n. As used by Tait and others, the available energy; that part of the energy which is not included under the entropy in sense .

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. (communication theory) a numerical measure of the uncertainty of an outcome
  • n. (thermodynamics) a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work


from The American Heritage® Dictionary of the English Language, 4th Edition

German Entropie : Greek en-, in; + Greek tropē, transformation.

from Wiktionary, Creative Commons Attribution/Share-Alike License

First attested in 1868. From German Entropie, coined in 1865 by Rudolph Clausius, from Ancient Greek ἐντροπία (entropia, "a turning towards"), from ἐν (en, "in") + τροπή (tropē, "a turning").


  • A typical rebuttal is to suggest that information entropy and thermodynamic entropy are unconnected, citing the apocryphal story that Shannon picked the term entropy because “nobody understands what it means”.

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  • In Über die bewegende Kraft der Wärme (1865) he introduced the term entropy, stating that the entropy of the universe tends to increase.

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  • Rudolf J.E. Clausius also introduced (1850) a quantitative measure of irreversibility which he termed entropy, and he posited the so-called second law of thermodynamics by which for a closed physical system the total entropy of the system cannot decrease in time but only increase or at most remain constant.


  • Fork in the Road, is entirely about his electric car, which he calls the entropy said: "This video made me smile and be happy, it's great to see people and robots getting along! ..." idontlikewords said: "I think what the author is getting at by bringing up the difference between an advertising medium an ..."

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  • It didn’t help that von Neuman and Shannon started using the term entropy for a formula in information theory that looked a lot like Boltzmann’s expression for entropy.

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  • Just as entropy is only a relative background effect, it is also not all that there is to reality.

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  • Social entropy is a similar concept applied to people - we have a tendency towards anarchy unless society applies extensive energy (laws, police, Dick Cheney, etc.) to rein us in.

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  • When it reaches that state, maximum entropy is achieved.

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  • With the advent of quantum mechanics in the 1920s (see Section 3.4), Eyring developed his transition-state theory in 1935 and this showed that the activation entropy is also important.

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  • This entropy is useful for all your random number needs.

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  • Inert uniformity. Sounds like the great silent majority in this and many countries you care to name

    August 12, 2010

  • What does it mean for energy to become untranslated?

    This word always reminds me of Thomas Pynchon.

    November 27, 2008

  • i once heard this used to describe a very personal state in which energy has lost its way, becomes stuck and untranslated.

    November 27, 2008

  • The Second Law of Thermodynamics specifies that entropy, the measure of randomness in a closed physical system, increases with time. Entropy is that physical phenomenon responsible for the inexorable expansion of the universe toward a state of complete dissipation of useful, creative if you will it, energy. This, crucially, does not obviate the possibility of temporary localized reductions in entropy, however.

    May 23, 2008

  • Great quote.

    April 13, 2008

  • "What's happening to your tea is happening to everything everywhere. The sun and the stars. It'll take a while but we're all going to end up at room temperature."

    (Tom Stoppard, Arcadia)

    April 12, 2008

  • This is also a term used in thermodynamics.

    November 11, 2007

  • Law & Order: Special Victims Unit - Season 6, Episode 3 - "Obscene"

    March 4, 2007