entropy

Pronunciation

• IPA: /ˈɛntɹəpi/^[1]

Etymology

It is borrowed from German Entropie,^[2][3][4][5] coined in 1865 by the physicist Rudolf Clausius on the analogy of Energie,^[4][5] from Ancient Greek ἐν (en, “in”) and Ancient Greek τροπή (tropḗ, “a turning, transformation”).^{[2][3][4][6][5]} Clausius intended the meaning “transformation content”.^[4]

Earliest recorded meaning

In thermodynamics, a quantity that determines the condition of a body of matter, measuring the energy not available for work (1868).^[3][4][7]

Semantic evolution

Clausius used the word to state the second law of thermodynamics: “the entropy of the universe tends toward a maximum”.^[4] In statistical mechanics it became a measure of randomness or disorder,^[2][5][6] and in communication theory, from 1948, a measure of the information in a message.^[7][2] By extension it means the tendency of the universe toward inert uniformity, and the steady decline of any system into disorder.^[2][6][1]

Timeline

• 1865 – German Entropie coined by Clausius.^[4][5]
• 1868 – in English.^[3][4][7]
• 1948 – in communication theory.^[7]
• 1951 – in mathematics generally.^[7]

Modern meaning

Noun

1. In thermodynamics, a measure of the energy in a closed system that is not available to do work.
2. A measure of the disorder or randomness of a system.
3. In information theory, a measure of the information in, or loss of information from, a transmitted message.
4. The supposed tendency of all matter and energy to reach a state of inert uniformity.
5. Steady, inevitable deterioration of a system or society.

Word family

• entropic
• entropically

Related words

• negentropy
• trope
• energy

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin
3. ^ a b c d Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
4. ^ a b c d e f g h Harper, Douglas, Online Etymology Dictionary, https://www.etymonline.com
5. ^ a b c d e Random House Webster's Unabridged Dictionary (1999), 2nd ed., New York: Random House
6. ^ a b c Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster
7. ^ a b c d e Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press