thorium
noun
tho·ri·um
ˈthȯr-ē-əm 
: a radioactive metallic element that is obtained especially from monazite and is usually associated with rare earths see Chemical Elements Table
Examples of thorium in a Sentence
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Byproducts include acidic wastewater, heavy metals, and radioactive elements like thorium and uranium.
—
Charlie Campbell, Time, 21 Apr. 2026
First, in most materials, the thorium nuclei release their energy not as light, but through a process called internal conversion, where the energy is transferred to an electron in the material instead.
—Andrei Derevianko, The Conversation, 14 Apr. 2026
Scientists from Xinjiang University in China have allegedly developed a new ultraviolet (UV) producing crystal that could help build extremely accurate thorium nuclear clocks.
—Christopher McFadden, Interesting Engineering, 12 Apr. 2026
The result suggests that heat-producing elements such as thorium may be more widely distributed beneath the lunar surface than previously thought, researchers say.
—Sharmila Kuthunur, Space.com, 3 Apr. 2026
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Charlie Campbell, Time, 21 Apr. 2026
First, in most materials, the thorium nuclei release their energy not as light, but through a process called internal conversion, where the energy is transferred to an electron in the material instead.
—Andrei Derevianko, The Conversation, 14 Apr. 2026
Scientists from Xinjiang University in China have allegedly developed a new ultraviolet (UV) producing crystal that could help build extremely accurate thorium nuclear clocks.
—Christopher McFadden, Interesting Engineering, 12 Apr. 2026
The result suggests that heat-producing elements such as thorium may be more widely distributed beneath the lunar surface than previously thought, researchers say.
—Sharmila Kuthunur, Space.com, 3 Apr. 2026
See All Example Sentences for thorium
Cite this Entry
“Thorium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/thorium. Accessed 1 May. 2026.
Copy CitationKids Definition
thorium
noun
tho·ri·um
ˈthōr-ē-əm
ˈthȯr-
: a radioactive metallic element see element
Medical Definition
thorium
noun
tho·ri·um
ˈthōr-ē-əm, ˈthȯr-
: a radioactive metallic element that occurs combined in minerals and is usually associated with rare earths
—symbol Th
see Chemical Elements Table
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