ther·​mo·​nu·​cle·​ar ˌthər-mō-ˈnü-klē-ər How to pronounce thermonuclear (audio)
-ˈn(y)ü-kyə-lər How to pronounce thermonuclear (audio)
: of, relating to, or employing transformations in the nuclei of atoms of low atomic weight (such as hydrogen) that require a very high temperature for their inception (as in the hydrogen bomb or in the sun)
thermonuclear reaction
thermonuclear weapon
: of, utilizing, or relating to a thermonuclear bomb
thermonuclear war
a thermonuclear attack

Examples of thermonuclear in a Sentence

Hydrogen bombs are thermonuclear weapons.
Recent Examples on the Web New Delhi has only conducted a handful of nuclear tests—not enough to validate its thermonuclear designs to offer high confidence that these weapons will perform as designed. Andrew F. Krepinevich Jr., Foreign Affairs, 26 May 2023 This was a thermonuclear device that was six times more powerful than the one the U.S. dropped on Hiroshima in 1945. Kim Hjelmgaard, USA TODAY, 19 Jan. 2024 Some scientists argue that the age of humans — also known as the Anthropocene era — began in 1952, when the U.S. tested its first thermonuclear bomb. Mansee Khurana, NPR, 3 Apr. 2024 Only four years later, the first thermonuclear weapon, Ivy Mike, was detonated, adding a new layer to the nuclear discussion. Christian Schneider, National Review, 21 Dec. 2023 Their fear of thermonuclear war did not prevent them from demanding that their government economically press the Communist world on human rights and the overall morality of its conduct. Christian Schneider, National Review, 21 Dec. 2023 His most interesting observation was that deterrence relies on credibility, but the threat of thermonuclear war in response to minor incursions was not credible. Christian Schneider, National Review, 21 Dec. 2023 This thermonuclear reaction creates vast amounts of light and heat, allowing the star to shine. Phil Plait, Scientific American, 10 Nov. 2023 One big challenge: Jackson needed to construct physical visualizations of subatomic activity leading up to the world’s first thermonuclear bomb explosion. Hugh Hart, Los Angeles Times, 13 Dec. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'thermonuclear.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


International Scientific Vocabulary

First Known Use

1938, in the meaning defined at sense 1

Time Traveler
The first known use of thermonuclear was in 1938

Dictionary Entries Near thermonuclear

Cite this Entry

“Thermonuclear.” Dictionary, Merriam-Webster, Accessed 24 Jun. 2024.

Kids Definition


ther·​mo·​nu·​cle·​ar ˌthər-mō-ˈn(y)ü-klē-ər How to pronounce thermonuclear (audio)
: of or relating to the transformations in the nucleus of atoms of low atomic weight (as hydrogen) that require a very high temperature (as in the hydrogen bomb or in the sun)
a thermonuclear reaction
a thermonuclear weapon

More from Merriam-Webster on thermonuclear

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