plutonium
noun
plu·to·ni·um
plü-ˈtō-nē-əm 
: a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy see Chemical Elements Table
Examples of plutonium in a Sentence
Recent Examples on the Web
Those reprocessing facilities handle commercial and defense-related nuclear waste, targeting material that can be separated into uranium and plutonium isotopes.
—
IEEE Spectrum, 7 July 2025
The Israeli military said the attack was designed to disable the core seal of the unfinished reactor and prevent it from being used to produce weapons-grade plutonium.
—Jesus Mesa, MSNBC Newsweek, 20 June 2025
Construction on the reactor, which Israel said was intended to produce weapons-grade plutonium for use in nuclear weapons, began in 1997 but was never completed.
—Nbc News, NBC news, 20 June 2025
In 1980, Glenn Seaborg, who was part of the team that first isolated plutonium, was able to turn several thousand atoms of the metallic element bismuth into gold by using a particle accelerator.
—Tom Bartlett, The Atlantic, 9 Aug. 2025
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IEEE Spectrum, 7 July 2025
The Israeli military said the attack was designed to disable the core seal of the unfinished reactor and prevent it from being used to produce weapons-grade plutonium.
—Jesus Mesa, MSNBC Newsweek, 20 June 2025
Construction on the reactor, which Israel said was intended to produce weapons-grade plutonium for use in nuclear weapons, began in 1997 but was never completed.
—Nbc News, NBC news, 20 June 2025
In 1980, Glenn Seaborg, who was part of the team that first isolated plutonium, was able to turn several thousand atoms of the metallic element bismuth into gold by using a particle accelerator.
—Tom Bartlett, The Atlantic, 9 Aug. 2025
See All Example Sentences for plutonium
Cite this Entry
“Plutonium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/plutonium. Accessed 29 Aug. 2025.
Copy CitationKids Definition
plutonium
noun
plu·to·ni·um
plü-ˈtō-nē-əm
: a radioactive metallic element that is formed by decay of neptunium and found in minute quantities in pitchblende and that produces atomic energy by fission see element
Medical Definition
plutonium
noun
plu·to·ni·um
plü-ˈtō-nē-əm
: a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy
—symbol Pu
see Chemical Elements Table
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