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

Wheeler helped design nuclear reactors to produce plutonium, the key element that allows the bomb to work. —Ken Bridges, Austin American-Statesman, 31 Dec. 2024

The lab is supposed to be building the capacity to produce thirty war-ready plutonium pits per year. —Abe Streep, The New Yorker, 27 Dec. 2024

These produce plutonium while simultaneously generating electricity. —Thomas Bass author, Newsweek, 19 Dec. 2024

Both spacecraft are powered by the heat from decaying plutonium that is converted into electricity. —Ashley Strickland, CNN, 4 Dec. 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