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

Whether Trump and Putin will ultimately agree to extend the nuclear agreement is unclear. Alex Ward, Vox, "The most important part of the Trump-Putin summit no one is talking about," 5 July 2018 Rouhani was in Vienna, where his country's nuclear agreement with world powers was drawn up three years ago, to promote the deal's survival after the withdrawal of the United States. Fox News, "Austria discusses Iran diplomat case with visiting Rouhani," 4 July 2018 Security experts have long warned that Tehran might respond to a collapse of the 2015 nuclear agreement by ramping up covert operations abroad, though more likely in the Middle East. Matthew Dalton, WSJ, "Four Arrested in Alleged Plot to Bomb Anti-Iran Gathering," 2 July 2018 Since May, prices have also been affected by Trump’s decisions to withdraw from the Iran nuclear agreement and to impose sanctions blocking American and most European companies from Iran’s market. Jake Meth, Fortune, "Trump Wants to Blame OPEC for High Oil Prices. But He’s Much More at Fault," 29 June 2018 Last month, President Trump withdrew the United States from the Iran nuclear agreement — despite the fact that Tehran had complied with the deal and that all of America’s allies supported its survival. Eric Levitz, Daily Intelligencer, "Trump Calls On Allies to Quit Buying Iranian Fuel. Oil Prices Spike.," 26 June 2018 Iran already is feeling the ill effects of Mr. Trump’s decision last month to withdraw the United States from the 2015 nuclear agreement and reimpose economic sanctions, which penalize businesses in other countries for doing business with Iran. New York Times, "Trump Travel Ban: How It Affects the Countries," 26 June 2018 After more than a half-century of hostility between the two countries, President Trump and Kim came face-to-face to try to strike a deal over the latter's nuclear weapons. Detroit Free Press Staff, Detroit Free Press, "What Dennis Rodman said on President Donald Trump, Kim Jung Un meeting," 11 June 2018 Then there’s the nuclear diplomacy with North Korea. Tony Abbott, WSJ, "An Ally Sizes Up Donald Trump," 13 July 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

7 Sep 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

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alleviating pain or harshness

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