plutonium

noun

plu·​to·​ni·​um plü-ˈtō-nē-əm How to pronounce plutonium (audio)
: 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 After the war, Leona's expertise in nuclear pile design led her to a job overseeing the operation and construction of the plutonium production reactors in Hanford, Washington. Erica Huang, Scientific American, 20 July 2023 The plutonium bomb acquired the nickname Fat Man; the uranium bomb was Little Boy. Kc Cole, Smithsonian Magazine, 8 Mar. 2024 The two Voyager probes are powered by plutonium, but that power system will eventually run out of juice. Nell Greenfieldboyce, NPR, 6 Mar. 2024 Japan has the shortest path to developing nuclear weapons, boasting both its own facilities for processing nuclear fuel and what is likely the world’s largest plutonium stockpile. Andrew S. Erickson, Foreign Affairs, 16 Feb. 2024 The lake’s sediment has preserved a record of human activity, including microplastics, evidence of burning fossil fuels and a measure of radioactive plutonium from testing nuclear weapons. Will Sullivan, Smithsonian Magazine, 6 Mar. 2024 The specific type on Voyager is called a radioisotope thermoelectric generator, which is a big name for what is basically a hunk of plutonium in a box. Rhett Allain, WIRED, 23 Feb. 2024 In 2020 a lab worker inhaled plutonium oxide powder—a terrifying prospect. Abe Streep, Scientific American, 10 Nov. 2023 Employees training to use glove boxes to handle plutonium. Time, 24 July 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'plutonium.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

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

First Known Use

1942, in the meaning defined above

Time Traveler
The first known use of plutonium was in 1942

Dictionary Entries Near plutonium

Cite this Entry

“Plutonium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/plutonium. Accessed 17 Apr. 2024.

Kids Definition

plutonium

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

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!