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

Situated in the southeast of the country, the plant is Ukraine's largest and houses six of its 15 operational nuclear power reactors. —Sam Meredith, CNBC, 27 Feb. 2026

This is made possible by the linear Boltzmann transport equation solver, which captures complex radiation behavior within the reactor core. —Georgina Jedikovska, Interesting Engineering, 27 Feb. 2026

In the month since NPR's original story, companies involved with the reactor program have rushed ahead with construction of their experimental designs. —Geoff Brumfiel, NPR, 26 Feb. 2026

But there is a small global community of enthusiasts who do, often by building home versions of a Farnsworth fusion reactor, or fusor. —Miriam Fauzia, Dallas Morning News, 26 Feb. 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)