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• nuclear fusion
  nuclear fusion

  noun

  fusion.
• fusion, nuclear
  fusion, nuclear

  The combining of two small atomic nuclei to form a larger nucleus, sometimes with the release of energy. (Compare nuclear fission.)

nuclear fusion

American  

[noo-klee-er fyoo-zhuhn, nyoo-] / ˈnu kli ər ˈfju ʒən, ˈnju- /

noun

1. fusion.

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nuclear fusion British  

noun

1. Sometimes shortened to: fusion.  a reaction in which two nuclei combine to form a nucleus with the release of energy Compare nuclear fission See also thermonuclear reaction

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fusion, nuclear Cultural  

1. The combining of two small atomic nuclei to form a larger nucleus, sometimes with the release of energy. (Compare nuclear fission.)

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Pronunciation

See nuclear ( def. ).

Discover More

The use of fusion as a controllable energy source on Earth is still in its experimental stages.

The fusion of hydrogen into helium releases huge amounts of energy and is the main energy source of stars, including the sun.

Hydrogen bombs use the energy of fusion.

Etymology

Origin of nuclear fusion

First recorded in 1895–1900

Example Sentences

See Examples For:

nuclear fusion fusion, nuclear

Researchers identified approximately 2,500 stars that have accumulated nearly all of the mass they need but have not yet begun nuclear fusion.

From Science Daily ● Jul. 5, 2026

This chemical makeup closely resembles the composition of the young universe, when almost all matter consisted of hydrogen and helium and heavier elements were only beginning to form inside massive stars through nuclear fusion.

From Science Daily ● Jul. 5, 2026

And helium-3 could also be used in some nuclear fusion reactors to one day create vast amounts of clean energy.

From BBC ● Jun. 16, 2026

Musk’s complaint also alleges that Altman engaged in self-dealing by directing OpenAI to pursue deals with companies in which he also held a personal stake, including nuclear fusion power company Helion.

From Los Angeles Times ● May 12, 2026

As these contracted, and the atoms within them collided with one another, the temperature of the gas would increase, until eventually it became hot enough to start nuclear fusion reactions.

From "A Brief History of Time: And Other Essays" by Stephen Hawking

For 75 years the U.S. federal government has invested heavily in fission and fusion nuclear power with only modest gains to show.

From Scientific American ● Jun. 5, 2023

Finally, fusion nuclear energy has achieved a breakthrough, thanks to the federal government and the work by some Seattle startups.

From Seattle Times ● Apr. 28, 2023

Its venture capital arm, Chevron Technology Ventures, is investing in new-energy start-ups like Zap Energy, which is developing modular fusion nuclear reactors that release no greenhouse gases and limit radioactive waste.

From New York Times ● Sep. 21, 2020