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

Without the sheltering benefit of solar wind, interstellar iron and plutonium would have battered the Earth. —Christian Thorsberg, Smithsonian Magazine, 14 June 2024

These robotic spacecraft safely launched and orbited Jupiter and Saturn, relying on plutonium power generators. —Stephen Clark, Ars Technica, 4 Apr. 2024

And all of this occurs while the plutonium is subject to more mundane chemical processes such as oxidation. —Scientific American, 19 Mar. 2024

Washington and Pattinson successfully pull off a highway heist in Tallinn, only to discover that the MacGuffin is not plutonium at all but something timey-wimey. —Nate Jones, Vulture, 26 Feb. 2024

Word History

Etymology

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

First Known Use

1942, in the meaning defined above

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