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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. 2015.
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Examples from the web for reactor
  • Likewise, the relationship between matter and energy isn't immediately useful unless you are building a nuclear reactor.
  • Tells about how atomic energy is released in a nuclear reactor.
  • The resulting spray shorted out electronics and forced an automatic shutdown of the nuclear reactor.
  • Even if the reactor shielding were ruptured, the alloy should keep seawater out of the rods for centuries.
  • At the core of the reactor's safety is a clever fuel design.
  • After the number four reactor exploded, entire communities were abandoned and hundreds of thousands of people relocated.
  • Winds can pick up radioactive material accidentally released from a nuclear reactor and scatter it around the world.
  • Animals and plants seem to be prospering near the infamous nuclear reactor.
  • We were not allowed to go near the reactor spaces, partly due to safety and partly due to military secrets.
  • Since this reactor has not been inspected often it is difficult to say when this may happen.
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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