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nuclear

American  
[noo-klee-er, nyoo-, -kyuh-ler] / ˈnu kli ər, ˈnju-, -kjə lər /

adjective

  1. pertaining to or involving atomic weapons.

    nuclear war.

  2. operated or powered by atomic energy.

    a nuclear submarine.

  3. (of a nation or group of nations) having atomic weapons.

  4. of, relating to, or forming a nucleus.

  5. of, relating to, or like the nuclear family.

    nuclear bonds.


noun

Informal.
  1. nuclear energy.

    switching to nuclear as a power source.

nuclear British  
/ ˈnjuːklɪə /

adjective

  1. of, concerned with, or involving the nucleus of an atom

    nuclear fission

  2. biology of, relating to, or contained within the nucleus of a cell

    a nuclear membrane

  3. of, relating to, forming, or resembling any other kind of nucleus

  4. of, concerned with, or operated by energy from fission or fusion of atomic nuclei

    a nuclear weapon

  5. involving, concerned with, or possessing nuclear weapons

    nuclear war

    a nuclear strike

"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 Scientific  
/ no̅o̅klē-ər /
  1. Relating to or forming a cell nucleus.

  2. Relating to atomic nuclei.

  3. Using energy derived from the nuclei of atoms through fission or fusion reactions.


Pronunciation

In pronouncing nuclear, the second and third syllables are most commonly said as , a sequence of sounds that directly reflects the spelled sequence ‑cle·ar. In recent years, a somewhat controversial pronunciation has come to public attention, with these two final syllables said as . Since , the common pronunciation of ‑cle·ar, might also be represented, broadly, as , the pronunciation can be seen as coming from a process of metathesis, in which the and the change places. The resulting pronunciation is reinforced by analogy with such words as molecular, particular, and muscular, and although it occurs with some frequency among highly educated speakers, including scientists, professors, and government officials, it is disapproved of by many.

Other Word Forms

Etymology

Origin of nuclear

1840–50; nucle(us) + -ar 1; compare French nucléaire

Explanation

Nuclear describes something that has to do with the nucleus — the central part — of an atom. If you're a nuclear physicist, you do a lot of work with that part of the atom. Nuclear power, which comes from nuclear fission — the energy released when the nucleus of an atom is split — is a controversial source of renewable energy. The word nuclear is sometimes used broadly to refer to the core of something. Your nuclear family is you, your parents, and your siblings — in a sense, the central part of your world, kind of like the nucleus of an atom.

Keep Reading on Vocabulary.com

Vocabulary lists containing nuclear

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.

See Examples For:

A drone struck a generator in May near the UAE's Barakah nuclear plant, the Arab world's only such facility, causing a fire.

From Barron's Jul. 22, 2026

The United States and Saudi Arabia have signed a nuclear cooperation agreement.

From BBC Jul. 22, 2026

The United Arab Emirates signed up for it, along with the gold standard of no domestic enrichment, as a condition of its 2009 nuclear deal negotiated largely with George W. Bush.

From The Wall Street Journal Jul. 22, 2026

Over the next two decades, the United States and Israel also targeted Syria’s nuclear and chemical weapons programs under Bashar al-Assad.

From Los Angeles Times Jul. 22, 2026

A nuclear reactor control room looks like something out of a classic Cold War movie.

From "Meltdown" by Deirdre Langeland

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