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

Lithium-7 fluoride, to be used in the molten salt reactor, is produced by solid-phase synthesis. —Prabhat Ranjan Mishra, Interesting Engineering, 12 Dec. 2025

Argentina was the first Latin American country to have a nuclear-research reactor, a product of the Atoms for Peace program. —Robin Wright, New Yorker, 12 Dec. 2025

That quake and tsunami left more than 22,000 people dead or missing and caused reactors at the Fukushima Daiichi nuclear power plant to melt down, releasing radioactive contamination into the surrounding area. —Billy Stockwell, CNN Money, 8 Dec. 2025

The plant's last reactor closed down in 2000. —Jeanine Santucci, USA Today, 6 Dec. 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)