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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

"That means you can't be powering this by nuclear fusion, which is the energy source that sits at the heart of all the stars we have."

From Science Daily ● Aug. 13, 2026

"You can't be powering this by nuclear fusion, which is the energy source that sits at the heart of all the stars," Naidu explained.

From Barron's ● Aug. 12, 2026

The company is still working to close a proposed merger with nuclear fusion company TAE Technologies.

From The Wall Street Journal ● Aug. 10, 2026

Empathy, the nuclear fusion of playwriting, is expanded when we’re allowed to take in more of our patchwork selves.

From Los Angeles Times ● Jun. 29, 2026

It assumes the existence of a nuclear fusion reactor— something much safer as well as more efficient than existing fission power plants.

From "Cosmos" by Carl Sagan

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