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
The agreements include a new science and technology partnership, civil nuclear cooperation and defense technology initiatives.
—Laura Daniella Sepulveda, AZCentral.com, 20 Sep. 2025
The critical mineral is needed for munitions, including missiles, some nuclear weaponry and other military equipment like night-vision goggles.
—Kevin Fixler
september 20, Idaho Statesman, 20 Sep. 2025
The ability to handle every step of the nuclear life cycle gives the Russian state an appealing offer to anyone who wants to spur domestic innovation.
—Suwanna Gauntlett Upjohn, Forbes.com, 19 Sep. 2025
The president’s role in nuclear command and control requires special consideration.
—Lynn Schmidt, Twin Cities, 19 Sep. 2025
See All Example Sentences for nuclear
Examples are automatically compiled from online sources to
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Laura Daniella Sepulveda, AZCentral.com, 20 Sep. 2025
The critical mineral is needed for munitions, including missiles, some nuclear weaponry and other military equipment like night-vision goggles.
—Kevin Fixler
september 20, Idaho Statesman, 20 Sep. 2025
The ability to handle every step of the nuclear life cycle gives the Russian state an appealing offer to anyone who wants to spur domestic innovation.
—Suwanna Gauntlett Upjohn, Forbes.com, 19 Sep. 2025
The president’s role in nuclear command and control requires special consideration.
—Lynn Schmidt, Twin Cities, 19 Sep. 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 24 Sep. 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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