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
However, that one didn't last long because there wasn't enough uranium fuel available and the molten salt design wasn't any good for making plutonium, so Oppenheimer et al went for a graphite reactor instead.
—
David Szondy, New Atlas, 17 Mar. 2025
Over the course of about 90 years, only half the plutonium in an RTG will have decayed away.
—Benjamin Roulston, The Conversation, 14 Mar. 2025
Others worked to prevent terrorists and rogue nations from acquiring weapons-grade plutonium or uranium.
—Geoff Brumfiel, NPR, 14 Feb. 2025
Modern thermonuclear weapons rely on what is called a plutonium pit.
—Andrew Paul, Popular Science, 9 Jan. 2025
See All Example Sentences for plutonium
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
David Szondy, New Atlas, 17 Mar. 2025
Over the course of about 90 years, only half the plutonium in an RTG will have decayed away.
—Benjamin Roulston, The Conversation, 14 Mar. 2025
Others worked to prevent terrorists and rogue nations from acquiring weapons-grade plutonium or uranium.
—Geoff Brumfiel, NPR, 14 Feb. 2025
Modern thermonuclear weapons rely on what is called a plutonium pit.
—Andrew Paul, Popular Science, 9 Jan. 2025
See All Example Sentences for plutonium
Cite this Entry
“Plutonium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/plutonium. Accessed 8 Apr. 2025.
Copy CitationKids 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share