nuclear

adjective

nu·​cle·​ar ˈnü-klē-ər How to pronounce nuclear (audio) ˈnyü- How to pronounce nuclear (audio)
 nonstandard  -kyə-lər
1
: of, relating to, or constituting a nucleus
annexation of the suburban fringe by the nuclear metropolisW. H. Wickwar
2
a
: 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
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.

Phrases
go nuclear
informal
: to become wildly excited or upset : 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

Examples of nuclear in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Given the riskier threat environment in East Asia due to China’s regional hegemonic ambitions and North Korea’s nuclear saber-rattling, Tokyo has little negotiating leverage. Jeff Kingston, Time, 4 Oct. 2025 Around 90 ships sailed through it last year, according to Rosatom, Russia’s state nuclear corporation, compared with the more than 13,000 that passed through the Suez Canal. Laura Paddison, CNN Money, 3 Oct. 2025 The court favored Holtec International, which was defending its right to discharge the Indian Point plant’s nuclear waste into the Hudson River. Prabhat Ranjan Mishra, Interesting Engineering, 3 Oct. 2025 Secretary of State Marco Rubio said 44 people and groups were targeted, including five individuals and one linked to Iran’s Organization of Defensive Innovation and Research (SPND), seen as the successor to Tehran’s pre-2004 nuclear weapons program. Amir Daftari, MSNBC Newsweek, 3 Oct. 2025 See All Example Sentences for nuclear

Word History

Etymology

nucle(us) + -ar

First Known Use

1822, in the meaning defined at sense 1

Time Traveler
The first known use of nuclear was in 1822

Browse Nearby Words

Cite this Entry

“Nuclear.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nuclear. Accessed 5 Oct. 2025.

Kids Definition

nuclear

adjective
nu·​cle·​ar ˈn(y)ü-klē-ər How to pronounce nuclear (audio)
1
: of, relating to, or being a nucleus (as of a cell)
2
: of, relating to, or using the atomic nucleus
nuclear reactions
3
: being or relating to energy or a weapon that involves a nuclear reaction
nuclear energy
a nuclear war
nuclear power plants

Medical Definition

nuclear

adjective
nu·​cle·​ar ˈn(y)ü-klē-ər How to pronounce nuclear (audio)
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

More from Merriam-Webster on nuclear

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