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[ree-ak-ter] /riˈæk tər/
a person or thing that reacts or undergoes reaction.
Electricity. a device whose primary purpose is to introduce reactance into a circuit.
Immunology, Veterinary Medicine. a patient or animal that reacts positively towards a foreign material.
Also called atomic pile, chain reactor, chain-reacting pile, nuclear reactor, pile. Physics. an apparatus in which a nuclear-fission chain reaction can be initiated, sustained, and controlled, for generating heat or producing useful radiation.
Chemistry. (especially in industry) a large container, as a vat, for processes in which the substances involved undergo a chemical reaction.
Origin of reactor
1885-90; 1940-45 for def 4; react + -or2
Related forms
nonreactor, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for reactor
Contemporary Examples
Historical Examples
  • This will give you a constant temperature inside the reactor.

    The K-Factor Harry Harrison (AKA Henry Maxwell Dempsey)
  • Father, do you remember when the Haval Valley reactor blew up?

    Ministry of Disturbance Henry Beam Piper
  • Obviously, the reactor was the only part not vaporized in the fall—because of its construction.

    A Fine Fix R. C. Noll
  • There were five other men in the reactor station, and—so far—he had seen no one.

    The Bramble Bush Gordon Randall Garrett
  • The head had vanished back into the control room of reactor Two.

    The Bramble Bush Gordon Randall Garrett
British Dictionary definitions for reactor


(chem) a substance, such as a reagent, that undergoes a reaction
short for nuclear reactor
a vessel, esp one in industrial use, in which a chemical reaction takes place
a coil of low resistance and high inductance that introduces reactance into a circuit
(med) a person sensitive to a particular drug or agent
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for reactor

"one that reacts," 1835, agent noun in Latin form from react. In nuclear sense, attested from 1945.

Online Etymology Dictionary, © 2010 Douglas Harper
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