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

Noteworthy is that a majority of Europe countries with phase-out policies have now reversed course, while others like Finland, Sweden, the UK, and Netherlands are all building or planning new reactors. —Scott Montgomery, Forbes.com, 30 Jan. 2026

Integration of advanced reactors and modern computing Beyond fuel management, these sites are also intended to host the deployment of advanced reactors and power generation facilities. —Aman Tripathi, Interesting Engineering, 29 Jan. 2026

Until now, the DOE's rules have typically applied to just a handful of reactors located on government property. —Geoff Brumfiel, NPR, 28 Jan. 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, 24 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)