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

The aim of such an attack would be to eliminate Iran’s air defenses, the report notes, paving the way for the Israeli military to strike at nuclear facilities hand-picked by the country’s intelligence. —Michael Lee, Fox News, 14 Apr. 2024

Dimona is home to Israel’s main nuclear facility, and Nevatim has a major air base. —Joseph Federman, Fortune, 14 Apr. 2024

The ultimate deal funneled tens of billions of dollars in sanctions relief to Iran and allowed the regime to become a greater conventional threat, all while preserving its nuclear ambitions in the long term. —The Editors, National Review, 14 Apr. 2024

Phiala Shanahan, a nuclear and particle physicist at the Massachusetts Institute of Technology, leads a team that computes the behavior of quarks and gluons starting from the equations of the strong force. —Charlie Wood, WIRED, 14 Apr. 2024

The Nuclear Medicine Clarification Act does not second-guess the radiation level that NRC has determined could indicate potential problems in handling nuclear materials. —Pam Kohl and Bill Kiser, STAT, 12 Apr. 2024

Leaders summit President Joe Biden will host the first-ever leaders summit between the US, Japan and the Philippines today, the latest attempt to draw Pacific allies closer as the region grapples with China’s aggression and nuclear provocations from North Korea. —Alexandra Banner, CNN, 11 Apr. 2024

Pompeii and nearby Herculaneum were seaside resorts favored by wealthy Romans when they were devastated by the eruption, which lasted for more than 24 hours and had the power of many thousands of nuclear bombs. —Patrick Smith, NBC News, 11 Apr. 2024

Starting in December 1960, for the first time in the nuclear age, the SIOP gave the president, not the military, control of America’s nuclear arsenal. —Annie Jacobsen, TIME, 11 Apr. 2024

Word History

Etymology

nucle(us) + -ar

First Known Use

1822, in the meaning defined at sense 1

Phrases Containing nuclear

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

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