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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
Another major story of Burnham’s concerned Karen Silkwood, an Oklahoma nuclear facility worker, whose suspicious death after being contaminated by plutonium became the subject of the 1983 Meryl Streep film Silkwood.
—Natalie Oganesyan, Deadline, 5 Oct. 2024
Voyager 2 has three radioisotope thermoelectric generators that power the spacecraft by converting heat emitted by the decaying plutonium into electricity.
—Jackie Wattles, CNN, 2 Oct. 2024
An array of radioactive substances had been released during the disaster, including plutonium and uranium, but scientists were also on the lookout for harmful levels of radioactive cesium and iodine isotopes, which turned out to be the abundant and far-reaching contaminants of agricultural land.
—Kate Graham-Shaw, Scientific American, 9 Oct. 2024
The revelatory images of North Korean leader Kim Jong Un touring a vast centrifuge hall, along with the recent startup of a reactor that may be producing plutonium and tritium for atomic weapons, heighten concerns over the rogue nation’s growing arsenal.
—Byrichard Stone, science.org, 23 Sep. 2024
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Word History
Etymology
New Latin, from Pluton-, Pluto, the planet Pluto
First Known Use
1942, in the meaning defined above
Dictionary Entries Near plutonium
Cite this Entry
“Plutonium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/plutonium. Accessed 15 Nov. 2024.
Kids 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
More from Merriam-Webster on plutonium
Nglish: Translation of plutonium for Spanish Speakers
Britannica.com: Encyclopedia article about plutonium
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