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

Takaichi also promised to speed the restart of reactors idled since the Fukushima nuclear plant disaster in 2011. —Reuters, NBC news, 20 Feb. 2026

Blue Capsule’s small modular reactor can provide 150 MW of heat at 700°C, steam/vapour to 650°C, and 50 MW of electricity. —Prabhat Ranjan Mishra, Interesting Engineering, 19 Feb. 2026

Helion is not yet assembling the fusion reactor, which requires additional engineering and design fine-tuning. —Jordan Blum, Fortune, 13 Feb. 2026

This is part of their sustainability goals and secures them part of the capacity from these reactors. —Anne T. Griffin, Forbes.com, 26 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)