re·​ac·​tor | \ rē-ˈak-tər How to pronounce reactor (audio) \

Definition of reactor

1 : one that reacts
2 : a device (such as a coil, winding, or conductor of small resistance) used to introduce reactance into an alternating-current circuit
3a : a vat for an industrial chemical reaction
b : a device for the controlled release of nuclear energy (as for producing heat)

Examples of reactor in a Sentence

Recent Examples on the Web The facility cost can be reduced by improving the efficiency of the catalyst and optimizing of the reactor. David Vetter, Forbes, 6 Sep. 2021 The ministry said about five out of more than 60,000 fuel-rod casings in the core of the reactor are damaged, less than 0.01% of the total and below the 0.25% maximum breakage assumed in the design. Chong Koh Ping, WSJ, 16 June 2021 Workers had been carrying out experiments with safety systems that led to a chain reaction of explosions which sent a fireball upwards and through the roof leading to a partial meltdown of the reactor. Amy Kellogg, Fox News, 27 Apr. 2021 Both were slow to admit that three of the reactor cores had suffered meltdowns, and have been criticized for downplaying bad news. Washington Post, 13 Apr. 2021 Three reactor cores exploded, releasing the highest amount of radioactivity in the environment since the Chernobyl nuclear disaster. Meagan Cantwell, Science | AAAS, 19 Mar. 2021 Because there was no way to cool the reactor cores, the nuclear fuel within them began to melt; amid fire, explosion and alarming amounts of radiation, a puddle from hell began eating into the plant’s concrete foundations. The Economist, 6 Mar. 2021 But what’s the real use case for using part of a small reactor’s output to make hydrogen? Caroline Delbert, Popular Mechanics, 14 Dec. 2020 Smaller reactor cores produce less radioactive material that could be released in an accident compared to traditional larger ones, proponents argue. Washington Examiner, 5 Aug. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'reactor.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of reactor

1890, in the meaning defined at sense 1

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Time Traveler for reactor

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The first known use of reactor was in 1890

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Last Updated

16 Sep 2021

Cite this Entry

“Reactor.” Dictionary, Merriam-Webster, Accessed 23 Sep. 2021.

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More Definitions for reactor



English Language Learners Definition of reactor

: a large device that produces nuclear energy


re·​ac·​tor | \ rē-ˈak-tər How to pronounce reactor (audio) \

Kids Definition of reactor

: a device using atomic energy to produce heat


re·​ac·​tor | \ rē-ˈak-tər How to pronounce reactor (audio) \

Medical Definition of reactor

1 : one that reacts: as
a : a chemical reagent
b : an individual reacting to a stimulus
c : an individual reacting positively to a foreign substance (as in a test for disease) reactors to tuberculin
2a : a piece of equipment in which a chemical reaction and especially an industrial chemical reaction is carried out
b : a device for the controlled release of nuclear energy (as for producing heat)

More from Merriam-Webster on reactor

Nglish: Translation of reactor for Spanish Speakers

Britannica English: Translation of reactor for Arabic Speakers Encyclopedia article about reactor


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