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 Niv Sultan stars as Tamar Rabinyan, a Mossad agent who was born in Iran but raised in Israel, sent on a high-risk mission to sneak into Iran and disable a nuclear reactor. Hank Stuever, Washington Post, "Expecting little, our TV critic found 25 shows worth watching this fall. (Yes, really!)," 10 Sep. 2020 The agency’s response to the latter report stated that those items will be further assessed when site-specific licensing applications—the step needed to actually begin building and operating a reactor—are submitted. David Levitan, Scientific American, "First U.S. Small Nuclear Reactor Design Is Approved," 9 Sep. 2020 The first ship, K-27, was a Soviet Navy submarine prototype equipped with a new liquid metal reactor. Kyle Mizokami, Popular Mechanics, "Russia's Sunken Nuclear Submarines Are a Chernobyl in Slow Motion," 4 Sep. 2020 An onboard nuclear reactor could supply it with electric power for decades, long enough for an array of MEGA drives to reach velocities approaching the speed of light. Daniel Oberhaus, Wired, "Gravity, Gizmos, and a Grand Theory of Interstellar Travel," 3 Sep. 2020 The first small modular reactor is scheduled to come online in 2029, with 11 more to follow in 2030. Keith Ridler, Star Tribune, "US gives first-ever OK for small commercial nuclear reactor," 2 Sep. 2020 The design also uses a passive cooling system, so no pumps or moving parts are required to keep the reactor operating safely. Scott K. Johnson, Ars Technica, "NuScale’s small nuclear reactor is first to get US safety approval," 1 Sep. 2020 Gates’ TerraPower, collaborating with GE Hitachi Nuclear Energy, plans to commercialize the new reactor and energy storage system in the U.S. in the late 2020s, the companies said. Josh Siegel, Washington Examiner, "Daily on Energy: California is Trump’s new campaign argument against Biden’s climate plans," 28 Aug. 2020 Standby diesel generators kicked in, giving power for the reactor's cooling systems, the NRC report said. Mike Hughlett, Star Tribune, "'Derecho' storm causes Cargill plant closure, emergency shutdown of nuclear plant in Iowa," 11 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

Time Traveler

The first known use of reactor was in 1890

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Last Updated

15 Sep 2020

Cite this Entry

“Reactor.” Dictionary, Merriam-Webster, Accessed 18 Sep. 2020.

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More Definitions for reactor


How to pronounce reactor (audio)

English Language Learners Definition of reactor

physics : 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)

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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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