plutonium

noun
plu·​to·​ni·​um | \ plü-ˈtō-nē-əm How to pronounce plutonium (audio) \

Definition of plutonium

: 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 In theory, the particles could reveal whether a reactor is building up plutonium for weapons. Sarah Scoles, Wired, 6 Oct. 2020 For many years, the predominant hypothesis was that heavy elements such as gold, silver, platinum, uranium and plutonium were created by the violent deaths of stars, called supernovae, reports Emily Conover for Science News. Alex Fox, Smithsonian Magazine, 17 May 2021 As a proof of principle, Cederwall and colleagues focused on detection of californium-252, a readily available radioisotope widely used as a proxy for weapons-grade plutonium. Richard Stone, Science | AAAS, 19 May 2021 The researchers say the rare iron and plutonium isotopes, iron-60 and plutonium-244, respectively, rained down on Earth sometime in the last ten million years before sinking nearly a mile to the bottom of the equatorial Pacific. Alex Fox, Smithsonian Magazine, 17 May 2021 Perseverance and Curiosity both make electricity from decaying radioactive plutonium. Chris Smith, BGR, 15 May 2021 The close copy of the B61-12 was equipped with almost every real-world component of the bomb except radioactive enriched uranium or plutonium. Kyle Mizokami, Popular Mechanics, 6 Apr. 2021 But in addition to tritium, more dangerous isotopes with longer radioactive lifetimes, such as ruthenium, cobalt, strontium, and plutonium, sometimes slip through the ALPS process, something TEPCO only acknowledged in 2018. Dennis Normile, Science | AAAS, 13 Apr. 2021 That bit of plutonium aboard the spacecraft runs its radio-thermal generator (RTG), a nuclear power source that should keep it operating until the late 2030s. Jeffrey Kluger, Time, 16 Apr. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'plutonium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of plutonium

1942, in the meaning defined above

History and Etymology for plutonium

New Latin, from Pluton-, Pluto, the planet Pluto

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Learn More About plutonium

Time Traveler for plutonium

Time Traveler

The first known use of plutonium was in 1942

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Last Updated

18 Jun 2021

Cite this Entry

“Plutonium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/plutonium. Accessed 24 Jun. 2021.

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More Definitions for plutonium

plutonium

noun

English Language Learners Definition of plutonium

: a radioactive element that is used to make nuclear energy and nuclear weapons

plutonium

noun
plu·​to·​ni·​um | \ plü-ˈtō-nē-əm How to pronounce plutonium (audio) \

Kids Definition of plutonium

: a radioactive metallic chemical element formed from neptunium and used for releasing atomic energy

plutonium

noun
plu·​to·​ni·​um | \ plü-ˈtō-nē-əm How to pronounce plutonium (audio) \

Medical Definition of plutonium

: 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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