thermonuclear

American  

[thur-moh-noo-klee-er, -nyoo-, -kyuh-ler] / ˌθɜr moʊˈnu kli ər, -ˈnju-, -kjə lər /

adjective

1. of, relating to, or involving a thermonuclear reaction.

   thermonuclear power.

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thermonuclear British  

/ ˌθɜːməʊˈnjuːklɪə /

adjective

1. involving nuclear fusion

   a thermonuclear reaction

   thermonuclear energy

2. involving thermonuclear weapons

   a thermonuclear war

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thermonuclear Scientific  

/ thûr′mō-no̅o̅′klē-ər /

1. Relating to the fusion of atomic nuclei at high temperatures or to the energy produced in this way.

2. Relating to weapons based on nuclear fusion, especially as distinguished from those based on nuclear fission.

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thermonuclear Cultural  

1. A term referring to devices that use nuclear fusion, the fusion of atomic nuclei, to produce energy at very high temperatures. (See hydrogen bomb.)

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Pronunciation

See nuclear.

Etymology

Origin of thermonuclear

First recorded in 1935–40; thermo- + nuclear

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Explanation

Something that has to do with high-temperature nuclear reactions is thermonuclear. Thermonuclear weapons are made using nuclear fusion. You'll almost always find the adjective thermonuclear describing the scientific process—it's a specific way to create fusion—or the resulting weapon. The word was first used around 1938 in reference to a process that occurs in stars. The first tests of a hydrogen bomb in the 1950s spawned the more common use of thermonuclear. The word combines the Greek thermos, "hot" and nuclear, "of the nucleus of a cell."

Example Sentences

See Examples For:

thermonuclear

The challenge that Churchill faced in 1940 was existential for Britain, but the one Eisenhower faced as president when the Cold War entered the thermonuclear age was existential on a global level.

From The Wall Street Journal ● Jun. 5, 2026

This setup, the report said, would allow launching sites to be “relatively invulnerable” to enemy warheads, requiring a “massive blanket Soviet thermonuclear attack” to destroy Iceworm launchers.

From Los Angeles Times ● Feb. 6, 2026

And it's exactly what he went against when going full thermonuclear on Rodgers on Monday.

From BBC ● Oct. 27, 2025

During his Nobel Peace Prize speech, Martin Luther King Jr. declared: “I refuse to accept the cynical notion that nation after nation must spiral down a militaristic stairway into the hell of thermonuclear destruction.”

From Salon ● Oct. 6, 2024

In other words, Teller was to have no formal authority at Livermore but was granted the implicit authority to direct its thermonuclear research program as he saw fit.

From "Big Science" by Michael Hiltzik

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