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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

Helium-3 has applications in quantum computing and nuclear fusion.

From BBC • Jun. 16, 2026

Massive stars produce light and heat through nuclear fusion, a process that releases enormous amounts of energy from their cores.

From Science Daily • Jun. 14, 2026

Actual power from nuclear fusion “has seemingly always been 10 to 20 years away,” Levin said.

From MarketWatch • May 18, 2026

However, as nuclear fusion attracts more public and private capital, Bechtel expects researchers to overcome these problems and make fusion a commercially viable source of energy by 2050.

From The Wall Street Journal • Apr. 6, 2026

When we look up at night and view the stars, everything we see is shining because of distant nuclear fusion.

From "Cosmos" by Carl Sagan