reactor

noun

re·​ac·​tor rē-ˈak-tər 

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

The company first submitted its construction permit application (CPA) in March 2024, becoming the first developer to do so for a commercial advanced reactor. —Aman Tripathi, Interesting Engineering, 25 Oct. 2025

The disaster also triggered a catastrophic failure at the Fukushima Daiichi Nuclear Power Plant, leading to meltdowns in three reactors and the release of radioactive material in what became the world’s worst nuclear crisis since Chernobyl. —Gabe Whisnant, MSNBC Newsweek, 24 Oct. 2025

But amid the blackout, the systems used to cool the reactors have run on emergency backup generators. —Simon Shuster, Time, 23 Oct. 2025

Heisenberg shared with Bohr a sketch of the German reactor, but Bohr cut off the discussion. —Literary Hub, 23 Oct. 2025

Word History

First Known Use

1890, in the meaning defined at sense 1

Phrases Containing reactor

• atomic reactor
• hyper-reactor
• nuclear reactor

Rhymes for reactor

• attractor
• cofactor
• compactor
• contactor
• contractor
• distractor
• extractor
• impactor
• protractor
• redactor
• refractor
• retractor

Kids Definition

reactor

noun

re·​ac·​tor rē-ˈak-tər 

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 

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)