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
see also:
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
Iran nuclear deal signed After a decade of unsuccessful attempts to rein in Iran’s nuclear ambitions, the Obama administration undertook a direct diplomatic approach beginning in 2013.
—Jeffrey Fields, The Conversation, 4 Apr. 2026
Almost no European ally believes the president’s assertion, the lynchpin of his justification for starting the war, that Iranian nuclear ambitions posed an imminent threat to either Israel or the West.
—Max Hastings, Mercury News, 4 Apr. 2026
The study set strict limits on these possible effects under certain assumptions and improved models of atomic and nuclear behavior.
—Georgina Jedikovska, Interesting Engineering, 4 Apr. 2026
The head of Russia’s state nuclear corporation, Rosatom, said that 198 workers were being evacuated.
—Sam Mednick, Los Angeles Times, 4 Apr. 2026
See All Example Sentences for nuclear
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Jeffrey Fields, The Conversation, 4 Apr. 2026
Almost no European ally believes the president’s assertion, the lynchpin of his justification for starting the war, that Iranian nuclear ambitions posed an imminent threat to either Israel or the West.
—Max Hastings, Mercury News, 4 Apr. 2026
The study set strict limits on these possible effects under certain assumptions and improved models of atomic and nuclear behavior.
—Georgina Jedikovska, Interesting Engineering, 4 Apr. 2026
The head of Russia’s state nuclear corporation, Rosatom, said that 198 workers were being evacuated.
—Sam Mednick, Los Angeles Times, 4 Apr. 2026
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 5 Apr. 2026.
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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