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

Liquid sodium has excellent heat transfer properties, allowing the reactor to operate at higher thermal efficiency and lower internal pressures. —Aman Tripathi, Interesting Engineering, 17 May 2026

The next-generation reactors, up to 300 MW (Mega Watts), are smaller than traditional reactors, easier to construct, safer, and more efficient. —Ian Dexter Palmer, Forbes.com, 4 May 2026

Fusion machines do not rely on the same process as traditional nuclear fission reactors and have different fuel cycles, waste streams, and safety characteristics, officials said. —Stephen Underwood, Hartford Courant, 3 May 2026

Oddly enough, at least one of Chernobyl's other reactors remained in use until 2000. —The Week Uk, TheWeek, 26 Apr. 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

• acter
• actor
• factor
• tractor
• attractor
• cofactor
• compactor
• contactor
• contractor
• distractor
• extractor
• impactor

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)