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nuclear energy

American  
[noo-klee-er en-er-jee, nyoo-] / ˈnu kli ər ˈɛn ər dʒi, ˈnyu- /

noun

  1. energy released by reactions within atomic nuclei, as in nuclear fission or fusion.

nuclear energy British  

noun

  1. Also called: atomic energy.  energy released during a nuclear reaction as a result of fission or fusion

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
nuclear energy Scientific  

  1. The energy released by the nucleus of an atom as the result of nuclear fission, nuclear fusion, or radioactive decay. The amount of energy released by the nuclear fission of a given mass of uranium is about 2,500,000 times greater than that released by the combustion of an equal mass of carbon. And the amount of energy released by the nuclear fusion of a given mass of deuterium is about 400 times greater that that released by the nuclear fission of an equal mass of uranium.

  2. Also called atomic energy

  3. Electricity generated by a nuclear reactor.

nuclear energy Cultural  

  1. Energy obtained from nuclear reactions.

Pronunciation

See nuclear ( def. ).

Etymology

Origin of nuclear energy

First recorded in 1925–30

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

However, Wang added, “China supports Iran’s efforts to safeguard its national sovereignty and security,” including its right to develop nuclear energy for peaceful purposes.

From Slate • May 7, 2026

SpaceX alumni have gone on to found companies focused on AI and robotics, nuclear energy and manufacturing.

From MarketWatch • May 7, 2026

The spacecraft, powered by a nuclear energy source, is gradually losing power, and shutting down this instrument is the most effective way to extend the life of humanity's first mission into interstellar space.

From Science Daily • May 4, 2026

He also reiterated his party's pledge to end a block on new nuclear energy and said he would make it a priority from "day one" if he became first minister.

From BBC • Apr. 23, 2026

But Dad’s main interest was energy: thermal energy, nuclear energy, solar energy, electrical energy, and energy from the wind.

From "The Glass Castle" by Jeannette Walls

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.