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

Longer-term, industry watchers expect that nuclear reactors — large, traditional facilities and small modular reactors — as well as wind and solar sources, backed up by more efficient storage batteries, will be viable options for powering data centers. —Bob Woods, CNBC, 11 Jan. 2026

This was an early NTP concept that called for a fission reactor paired with liquid-hydrogen propellant. —Matthew S Williams, Interesting Engineering, 10 Jan. 2026

Further research found that these natural reactors were not continuously in operation but cycled on and off over hundreds of thousands of years. —New Atlas, 8 Jan. 2026

The vessel had patrolled during the same years as the Growler but, in 1961, suffered a reactor incident that radiated its crew. —Robert Sullivan, New Yorker, 5 Jan. 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)