re·​ac·​tor | \rē-ˈak-tər \

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

In contrast, fast reactors split atoms with the raw high-energy neutrons. Adrian Cho, Science | AAAS, "Congress pushes for multibillion-dollar nuclear reactor that critics call a boondoggle," 3 July 2018 At first, the Trump administration said the North must give up all enrichment of uranium, which can fuel not only bombs but reactors that illuminate cities. New York Times, "North Korea Nuclear Disarmament Could Take 15 Years, Expert Warns," 28 May 2018 Nuclear energy now accounts for less than 2 percent of Japan's energy mix since most reactors were idled after the 2011 disaster. Fox News, "Japan draft plan sets ambitious targets for nuclear energy," 16 May 2018 In October 2016, Iran slightly surpassed a limit on its stockpiles of heavy water, which is used in medical imaging and can also fuel reactors that produce plutonium, a weapons material., "Mario Draghi Answers Questions at ECB News Conference," 24 Apr. 2018 What to do with Chernobyl has vexed governments in Kiev since the nuclear plant’s remaining reactors were finally mothballed in 2000. Time, "Chernobyl Is Now the World’s Unlikeliest Green Energy Experiment," 13 Mar. 2018 The plant's reactors, which are now billions of dollars over budget, are not expected to be in service until 2021 and 2022 at the earliest. Megan Geuss, Ars Technica, "Budget deal has tax credit extensions for nuclear, fuel cells, carbon capture," 9 Feb. 2018 Fusion reactors, which are not yet good enough for commercial use, can be nightmarish tangles of technology that are damn near impossible to fully understand. Eric Limer, Popular Mechanics, "Everything You Should Know About Nuclear Fusion, Explained in Six Minutes," 10 Nov. 2016 These reactors have proven unaffordable and economically uncompetitive. David Roberts, Vox, "The US is rapidly losing nuclear power. That’s profoundly concerning for climate change.," 11 July 2018

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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Last Updated

5 Nov 2018

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Time Traveler for reactor

The first known use of reactor was in 1890

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English Language Learners Definition of reactor

physics : a large device that produces nuclear energy


re·​ac·​tor | \rē-ˈak-tər \

Kids Definition of reactor

: a device using atomic energy to produce heat


re·​ac·​tor | \rē-ˈak-tər \

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)

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Comments on reactor

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to clear from alleged fault or guilt

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