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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
Recent Examples on the Web
Helium is formed by the radioactive decay of uranium and thorium deep inside the earth’s crust.
—Michael Braga, The Arizona Republic, 14 May 2024
In 2003 physicists first suggested that a synthetic isotope called thorium 229 could be the key to nuclear timekeeping.
—Kenna Hughes-Castleberry, Scientific American, 20 Oct. 2023
But one stood out: shooting protons at targets made of thorium 232.
—Sarah Scoles, Scientific American, 13 Feb. 2024
Although uranium and thorium have been widely-detected on Mars, Zubrin predicts that the technology to support the large-scale settlement of Mars is fusion power.
—Bruce Dorminey, Forbes, 18 Feb. 2024
There’s a resistance to processing, particularly heavy rare earths that tend to come coupled together with uranium and thorium.
—IEEE Spectrum, 7 Dec. 2023
In the study, a team of physicists at CERN's nuclear physics facility, ISOLDE, spotted and measured thorium 229's nuclear transition for the first time.
—Kenna Hughes-Castleberry, Scientific American, 20 Oct. 2023
Over time, minerals accumulate energy as radioactive elements like uranium, thorium, and potassium decay and release radiation.
—Paul Bierman, Fortune, 24 July 2023
Phoenix finds mine sites where the tailings waste is free from radioactive elements such as thorium and uranium.
—Yusuf Khan, WSJ, 20 July 2023
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'thorium.' 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 Old Norse Thōrr Thor
First Known Use
1832, in the meaning defined above
Dictionary Entries Near thorium
Cite this Entry
“Thorium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/thorium. Accessed 13 Jun. 2024.
Kids 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
More from Merriam-Webster on thorium
Britannica.com: Encyclopedia article about thorium
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