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 reactor facilitates rapid heat dissipation, preventing the thermal runaway that typically degrades catalysts. —Mrigakshi Dixit, Interesting Engineering, 5 Feb. 2026

First American Nuclear is dedicated to building small modular reactors, or SMRs, which are advanced nuclear reactors that have about one-third the generating capacity of traditional nuclear reactors, according to the International Atomic Energy Agency. —Maya Wilkins, Chicago Tribune, 4 Feb. 2026

Big Tech has the capital and the ambition to pursue nuclear, including next generation reactor designs which match very well the sector’s self-image of innovative strength at the leading edge of technological change. —Scott Montgomery, Forbes.com, 30 Jan. 2026

These installations can include renewable generation, usually solar and batteries; different forms of nuclear energy—from restarting entire power plants to investing in small modular reactors—are also popular choices for tech companies. —Molly Taft, Wired News, 21 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)