reactor

American  

[ree-ak-ter] / riˈæk tər /

noun

• reactors
  plural

1. a person or thing that reacts or undergoes reaction.

2. Electricity. a device whose primary purpose is to introduce reactance into a circuit.

3. Immunology, Veterinary Medicine. a patient or animal that reacts positively towards a foreign material.

4. Physics. nuclear reactor.

5. Chemistry. (especially in industry) a large container, as a vat, for processes in which the substances involved undergo a chemical reaction.

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reactor British  

/ rɪˈæktə /

noun

1. chem a substance, such as a reagent, that undergoes a reaction

2. short for nuclear reactor

3. a vessel, esp one in industrial use, in which a chemical reaction takes place

4. a coil of low resistance and high inductance that introduces reactance into a circuit

5. med a person sensitive to a particular drug or agent

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Other Word Forms

Derived Forms

• nonreactor
  noun

Inflected Forms

Nouns

• reactors
  plural

Etymology

Origin of reactor

First recorded in 1885–90; 1940–45 reactor for def. 4; react + -or ²

Explanation

A reactor is where a nuclear reaction is controlled, making it possible to create energy or any number of artificial elements. Reactor these days almost always refers to a nuclear reactor, where atomic fission of uranium or plutonium creates the heat used to make steam to generate electricity. Originally, though, reactor meant a vessel in which chemical processes were made to generate useful products such as nylon and artificial sweetener. These reactors are still used in chemical manufacturing plants.

Example Sentences

See Examples For:

reactor reactors

The country no longer has any reactor that its natural uranium metal could fuel, so it might as well hand over the material and ship it out.

From The Wall Street Journal ● Aug. 19, 2026

Syria also procured large amounts of graphite needed to keep the nuclear reactions in the reactor steady.

From The Wall Street Journal ● Aug. 18, 2026

No developers outside China and Russia have yet completed a commercial version of what’s known as a small modular reactor, or SMR.

From The Wall Street Journal ● Aug. 18, 2026

“Because this is a smaller reactor doesn’t mean a smaller design effort because it’s still fission.”

From The Wall Street Journal ● Aug. 18, 2026

For people who spent their workdays watching the ups and downs of reactor pressure and heat, and making constant adjustments to keep things running safely, it was a worst-case scenario.

From "Meltdown" by Deirdre Langeland

Major arteries for trade and agriculture across the continent are now at record low levels, disrupting freight transportation, forcing nuclear power plants to shut reactors and eroding agricultural productivity.

From The Wall Street Journal ● Aug. 18, 2026

Eventually, Oklo plans to build more than a dozen reactors at an Ohio campus that could generate up to 1.2 gigawatts of electricity, enough to power 1,200 Walmarts.

From The Wall Street Journal ● Aug. 18, 2026

In the coming years, he said India will have eight more semiconductor chip plants and five nuclear reactors which will generate 100 gigawatts of power by 2047.

From Barron's ● Aug. 15, 2026

The result provides the first direct experimental confirmation of predictions describing antineutrino emissions from shut down reactors and spent fuel.

From Science Daily ● Aug. 14, 2026

There was one major difference between the fuel in the spent storage pools and the fuel inside the reactors.

From "Meltdown" by Deirdre Langeland