reactor

American  

[ree-ak-ter] / riˈæk tər /

noun

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

• nonreactor noun

Etymology

Origin of reactor

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

Example Sentences

Not everyone is fully on board, however — including Isaacman, whose ambitious plans involve developing a lunar nuclear reactor by 2030.

From MarketWatch • Mar. 31, 2026

The sun’s mass makes it a gravity-powered fusion reactor, but on Earth, scientists need other ways to create plasma—a superheated, electrically charged gas—and confine it to force atoms to collide.

From The Wall Street Journal • Mar. 28, 2026

That would not fuel a single reactor for a single year.

From MarketWatch • Mar. 26, 2026

The Shimon Peres Negev Nuclear Research Center - located in the Negev desert - is often referred to colloquially as the "Dimona reactor".

From BBC • Mar. 21, 2026

At Chernobyl, the nuclear reactor actually exploded, spewing material from the reactor’s core straight into the atmosphere.

From "Meltdown" by Deirdre Langeland