Etymologically
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reactor

This is the current revision of this entry, as edited by bogdan on 22 October 2026 at 21:07. This address is a permanent link to this version.
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Pronunciation

  • UK: /ɹiːˈæktə/[1]
  • US: /ɹiˈæktɚ/[1]

Etymology

It is formed from English react + -or.[2][3] Its first sense, a reactionary of the French Revolution, followed French réacteur (1794).[2] Barnhart first records the word in 1890 as reacter, in William James's The Principles of Psychology, with the spelling reactor from 1895.[3]

Earliest recorded meaning

A reactionary, especially a Thermidorian of the French Revolution: 1836, in a New York translation of Lucien Bonaparte's memoirs.[2] Etymonline dates "one that reacts" to 1835,[4] and Merriam-Webster gives 1890.[5]

Semantic evolution

The general sense, a person or organism that reacts to a stimulus, especially in an experiment, dates from 1890.[2][3] Medicine and veterinary medicine used it from 1908 for a patient or animal that reacts positively in a test for a disease, especially tuberculosis.[2] Chemistry gave it the sense of a vessel in which substances react (1903), electrical engineering a coil that provides reactance (1915),[2][4] and physics, in 1945, the apparatus in which a controlled nuclear chain reaction takes place, first in the term nuclear reactor.[2][3][4]

Timeline

  • 1836 – a reactionary in French history.[2]
  • 1890 – one that reacts to a stimulus.[2][3]
  • 1903 – a vessel for chemical reactions.[2]
  • 1908 – a patient or animal reacting positively to a test.[2]
  • 1915 – a coil providing reactance.[2][4]
  • 1945 – a nuclear reactor.[2][3][4]

Modern meaning

Noun

  1. An apparatus in which a controlled nuclear chain reaction takes place, typically to generate power; a nuclear reactor.
  2. A vessel or apparatus in which substances are made to react chemically.
  3. (electronics) A coil or other component that introduces reactance into a circuit.
  4. (medicine) A person or animal that reacts to a drug or shows a positive reaction in a test.
  5. Someone or something that reacts to a stimulus.

Word family

  • nonreactor
  • atomic reactor
  • breeder reactor
  • fast-breeder reactor
  • fusion reactor
  • nuclear reactor

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h i j k l m Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d e f Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  4. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  5. ^ Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster