nuclear

adjective

nu·​cle·​ar ˈnü-klē-ər  ˈnyü- 

 nonstandard  -kyə-lər

1

: of, relating to, or constituting a nucleus

annexation of the suburban fringe by the nuclear metropolis

—W. 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

North Korea, which has faced years of international sanctions over its nuclear weapons program, has ramped up its weapons tests and military exercises in recent weeks. —Brad Lendon, CNN, 2 Apr. 2024

The missile launch comes days after Russia vetoed a United Nations resolution that monitors enforcement of nuclear sanctions against the North Korean government. —Andrea Vacchiano, Fox News, 1 Apr. 2024

In World War II, the U.S. dropped nuclear bombs on the two Japanese cities Walberg referenced in an effort to bring to an end a conflict that would ultimately cost 15 million lives on battlefields worldwide. —Todd Spangler, Detroit Free Press, 30 Mar. 2024

The Catcher Was a Spy: Moe Berg, a Major League Baseball player, becomes a World War II spy, undertaking dangerous missions in Europe to gather intelligence and thwart Nazi nuclear ambitions. —Travis Bean, Forbes, 29 Mar. 2024

Hiroyuki Shinju, a lawyer, noted Japan and Germany also carried out wartime atrocities, even as the nuclear threat grows around the world. —Yuri Kageyama, The Christian Science Monitor, 29 Mar. 2024

The government will invest £353 million ($445 million) in apprenticeships and skills in the defense and civil nuclear sector by 2030. —Kit Rees, Fortune Europe, 25 Mar. 2024

The authority would delve into workforce and educational needs to develop the nuclear industry in Kentucky. —Bruce Schreiner, Quartz, 22 Mar. 2024

Moreover, many Germans fear Russian retaliation because the country does not have a nuclear deterrent of its own. —Joseph De Weck, The Atlantic, 20 Mar. 2024

Word History

Etymology

nucle(us) + -ar

First Known Use

1822, in the meaning defined at sense 1

Phrases Containing nuclear

• nuclear capability
• go nuclear
• nuclear energy
• nuclear family
• nuclear magnetic resonance
• nuclear-free
• nuclear fission
• nuclear fusion
• nuclear power
• nuclear membrane
• nuclear option
• nuclear medicine
• post-nuclear
• nuclear winter
• nuclear sap
• nuclear reaction
• nuclear reactor

Video

'Mispronunciations' That May Be Fine

'Mischievous,' 'nuclear,' and other words to pronounce with caution.

Kids Definition

nuclear

adjective

nu·​cle·​ar ˈn(y)ü-klē-ər 

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 

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