nuclear
adjective
nu·cle·ar
ˈnü-klē-ər 
ˈnyü-
ˈnyü-
nonstandard -kyə-lər
1
: of, relating to, or constituting a nucleus
annexation of the suburban fringe by the nuclear metropolis—
W. H. Wickwar
W. H. Wickwar2
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
Tony KornheiserExamples of nuclear in a Sentence
Recent Examples on the Web
Israel, already emerging from a year of history-bending military operations—crippling Hamas in Gaza, decapitating Hezbollah's command structure, and setting back Iran's nuclear program—now stands at the threshold of something larger.
—Eric Cortellessa, Time, 11 Oct. 2025
Blinky became a symbolic picture for real-world commentary regarding the dangers of mutation and nuclear waste, and in 2011, a real-life three-eyed wolf fish was caught near an Argentinian nuclear plant, per ZME Science.
—Zoe Kaplan, PEOPLE, 11 Oct. 2025
Despite taking place at the White House, the actress explained how the film is not meant to reflect current political times but, instead, raises questions about who holds authority over nuclear weapons.
—Giana Levy, Variety, 11 Oct. 2025
Like that’s going to do any good at all in case of a nuclear explosion.
—Antonia Blyth, Deadline, 10 Oct. 2025
See All Example Sentences for nuclear
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Eric Cortellessa, Time, 11 Oct. 2025
Blinky became a symbolic picture for real-world commentary regarding the dangers of mutation and nuclear waste, and in 2011, a real-life three-eyed wolf fish was caught near an Argentinian nuclear plant, per ZME Science.
—Zoe Kaplan, PEOPLE, 11 Oct. 2025
Despite taking place at the White House, the actress explained how the film is not meant to reflect current political times but, instead, raises questions about who holds authority over nuclear weapons.
—Giana Levy, Variety, 11 Oct. 2025
Like that’s going to do any good at all in case of a nuclear explosion.
—Antonia Blyth, Deadline, 10 Oct. 2025
See All Example Sentences for nuclear
Video
'Mispronunciations' That May Be Fine
'Mischievous,' 'nuclear,' and other words to pronounce with caution.
Cite this Entry
“Nuclear.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nuclear. Accessed 18 Oct. 2025.
Copy CitationKids 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
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