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 March 11, 2011, quake and tsunami destroyed cooling systems at the Fukushima Daiichi plant, causing meltdowns at reactors 1, 2 and 3. —Arkansas Online, 21 Mar. 2026

The drones also collected radiation measurements and data to produce a detailed three-dimensional map of the inside of the Unit 3 reactor, Kuwajima said. —ABC News, 20 Mar. 2026

The reactor — which can produce nuclear material for medical purposes — is powered by 20%-enriched uranium, which is a significant step toward the 90%-enriched material used in weapons. —Joe Walsh, CBS News, 20 Mar. 2026

Company can further refine the reactor’s safety framework The agreement builds on earlier arrangements between Oklo and the Department of Energy, reinforcing collaboration aimed at accelerating innovative nuclear technologies. —Prabhat Ranjan Mishra, Interesting Engineering, 18 Mar. 2026

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)