nu·​cle·​ar | \ˈnü-klē-ər, ˈnyü-, nonstandard -kyə-lər \

Definition of nuclear 

1 : of, relating to, or constituting a nucleus annexation of the suburban fringe by the nuclear metropolis— W. H. Wickwar

2a : of or relating to the atomic nucleus nuclear reaction nuclear physics

b : used in or produced by a nuclear reaction (such as fission) nuclear fuel nuclear waste nuclear energy

c(1) : being a weapon whose destructive power derives from an uncontrolled nuclear reaction

(2) : of, produced by, or involving nuclear weapons the nuclear age nuclear war

(3) : armed with nuclear weapons nuclear powers

d : of, relating to, or powered by nuclear energy a nuclear submarine the nuclear debate a nuclear plant

go nuclear

: to become wildly excited or upset : to go berserk To say the crowd went wild is an understatement. The crowd went nuclear. Outside the stadium, cars were overturned and fires were set. We sportswriters huddled inside, fearing for our lives.— Tony Kornheiser

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How do you pronounce nuclear?: Usage Guide

Though disapproved of by many, pronunciations ending in \-kyə-lər\ have been found in widespread use among educated speakers including scientists, lawyers, professors, congressmen, U.S. cabinet members, and at least two U.S. presidents and one vice president. While most common in the U.S., these pronunciations have also been heard from British and Canadian speakers.

Examples of nuclear in a Sentence

Recent Examples on the Web

The nuclear deal offered the promise of economic improvement but mostly enriched the ayatollahs. Eliora Katz, WSJ, "Iranians Are Now Chanting ‘Death to Palestine’," 13 July 2018 Over the opposition of European allies, the president in May pulled out from the 2015 nuclear deal involving Iran, the United States, and other world powers. Matthew Lee,, "Trump says there ‘might be an escalation’ between US, Iran," 12 July 2018 In Singapore, summitry made sense if it was meant to halt the rhetorical war between Trump and Kim and to advance the dismantling of North Korea’s nuclear program. Trudy Rubin,, "Trump thinks his personal relationships with dictators will save the world. He's wrong | Trudy Rubin," 15 June 2018 More broadly, Chinese commentators have suggested Beijing also could disrupt diplomatic work over North Korea’s nuclear and missile programs or other initiatives. San Antonio Express-News, "China’s options to hit US go beyond imports," 9 July 2018 That was at the height of Washington-Pyongyang tensions, when the chance of nuclear war was higher than zero percent. Alex Ward, Vox, "We need to talk about the fact that Trump seriously considered invading Venezuela," 6 July 2018 Politically, impeachment is the equivalent of nuclear war, and many Democrats fear merely brandishing the threat will backfire, antagonizing Republicans and energizing conservative voters who might otherwise skip the midterm vote. Mark Z. Barabak,, "Impeach Trump? Even Democrats who despise the president can't agree on a strategy for the midterm election," 25 June 2018 To the president the summit was a historic achievement moving the world away from nuclear war. NBC News, "Meet the Press - June 17, 2018," 17 June 2018 President Trump says his deal with North Korea's Kim Jong Un will save tens of millions of people from a potential nuclear war. CBS News, "Trump grumbles that deal with North Korea isn't getting enough praise," 16 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'nuclear.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of nuclear

1822, in the meaning defined at sense 1

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Statistics for nuclear

Last Updated

19 Oct 2018

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Time Traveler for nuclear

The first known use of nuclear was in 1822

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English Language Learners Definition of nuclear

: of, relating to, producing, or using energy that is created when the nuclei of atoms are split apart or joined together

: having or involving nuclear weapons

: of or relating to the nucleus of an atom


nu·​cle·​ar | \ˈnü-klē-ər, ˈnyü-\

Kids Definition of nuclear

1 : of, relating to, or being a nucleus (as of a cell)

2 : of or relating to the nucleus of the atom Fission is a nuclear reaction.

3 : produced by a nuclear reaction nuclear energy

4 : of, relating to, or being a weapon whose destructive power comes from an uncontrolled nuclear reaction

5 : relating to or powered by nuclear energy a nuclear submarine


nu·​cle·​ar | \ˈn(y)ü-klē-ər \

Medical Definition of nuclear 

1 : of, relating to, or constituting a nucleus

2 : of, relating to, or utilizing the atomic nucleus, atomic energy, the atomic bomb, or atomic power

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More from Merriam-Webster on nuclear

Spanish Central: Translation of nuclear

Nglish: Translation of nuclear for Spanish Speakers

Britannica English: Translation of nuclear for Arabic Speakers

Comments on nuclear

What made you want to look up nuclear? Please tell us where you read or heard it (including the quote, if possible).


something that serves to warn or remind

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