nu·​cle·​ar | \ ˈnü-klē-ər How to pronounce nuclear (audio) , ˈnyü- How to pronounce nuclear (audio) , 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 They are accused of using $60 million in bribes given by FirstEnergy to pass a $1.3 billion bailout benefiting two nuclear power plants and increase the speaker’s power. Jeremy Pelzer, cleveland, "Ohio lawmakers seek to repeal another bill benefiting FirstEnergy -- this time, over ‘excessive’ profits," 30 July 2020 Last September, malware affected an Indian nuclear power plant. Christopher Martin,, "Hackers are targeting the remote workers who keep your lights on," 30 July 2020 Its nuclear power pack was installed on July 20 and on Tuesday, the rocket and its payload were hauled to launch complex 41 for final preparations. William Harwood, CBS News, "NASA readies launch of Mars rover to look for signs of past life, collect samples for return to Earth," 28 July 2020 Formula One racing in Austria, the empty streets of Pamplona, a zoo re-opening in Ecuador, a nuclear power plant in France, a wildfire in California, and much more. Alan Taylor, The Atlantic, "Photos of the Week: Chicken Offering, Virginia Creeper, Comet Neowise," 10 July 2020 Sanders explicitly opposed nuclear power during the campaign. Abby Smith, Washington Examiner, "Daily on Energy: Pandemic’s deep carbon reductions have come with a huge price tag," 9 July 2020 Iran has long said its nuclear program is for peaceful energy generation. David Clark Scott, The Christian Science Monitor, "Monday Sunrise Briefing: Security and equality shape US campaign," 6 July 2020 Messmer’s announcement was a plan to construct 80 nuclear-power plants over the following decade, and 170 by the turn of the century. The Economist, "If nuclear power had taken off What if nuclear power had taken off in the 1970s?," 4 July 2020 Achieving that goal is made harder than in comparable countries such as France and Britain because of Germany’s existing commitment to also phase out nuclear power by the end of 2022. Washington Post, "Germany is first major economy to phase out coal and nuclear," 3 July 2020

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

History and Etymology for nuclear

nucle(us) + -ar

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Time Traveler for nuclear

Time Traveler

The first known use of nuclear was in 1822

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Statistics for nuclear

Last Updated

5 Aug 2020

Cite this Entry

“Nuclear.” Dictionary, Merriam-Webster, Accessed 14 Aug. 2020.

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More Definitions for nuclear


How to pronounce nuclear (audio) How to pronounce nuclear (audio)

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 How to pronounce nuclear (audio) , 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 How to pronounce nuclear (audio) \

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

Thesaurus: All synonyms and antonyms for 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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