reactor

noun

re·​ac·​tor rē-ˈak-tər How to pronounce reactor (audio)
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
3
a
: 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Scale changes reactor economics Traditional nuclear projects often require highly specialized components designed around individual plants. — Aamir Khollam, Interesting Engineering, 2 Sep. 2026 The August 26 announcement is part of the Army's Janus Program, which is tasked with developing stationary and transportable micro-reactors for defense applications. — David Szondy august 31, New Atlas, 1 Sep. 2026 See All Example Sentences for reactor

Word History

First Known Use

1890, in the meaning defined at sense 1

Time Traveler
The first known use of reactor was in 1890

Phrases Containing reactor

Rhymes for reactor

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Browse Nearby Words

reactology
reactor
reactualization
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Cite this Entry

“Reactor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/reactor. Accessed 2 Sep. 2026.

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Kids Definition

reactor

noun
re·​ac·​tor rē-ˈak-tər How to pronounce reactor (audio)
1
: one that reacts
2
: a device for the controlled release of nuclear energy (as for producing heat)

Medical Definition

reactor

noun
re·​ac·​tor rē-ˈak-tər How to pronounce reactor (audio)
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
2
a
: 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

Britannica.com: Encyclopedia article about reactor

Last Updated: - Updated example sentences
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