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

Unlike larger experimental reactors, this tabletop unit allows for frequent, hands-on use by students and faculty. —Aman Tripathi, Interesting Engineering, 13 Mar. 2026

South Korea too has vowed to speed up its reactor restart. —Jeronimo Gonzalez, semafor.com, 11 Mar. 2026

Some of those changes have included bringing the previously autonomous agency under the White House Office of Management and Budget, who can now review and approve reactor safety rules – a departure from past years. —Ella Nilsen, CNN Money, 10 Mar. 2026

Now, for the first time since the disaster, all of the plant’s reactor buildings have their rooftops enclosed. —ABC News, 10 Mar. 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)