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

These were accompanied by supposed paper records confirming it to be thorium and uranium. —Andrew Paul, Popular Science, 9 Jan. 2025

In this kind of reactor, thorium fluoride dissolves in molten salt in the reactor’s core. —Emily Waltz, IEEE Spectrum, 30 Dec. 2024

Copenhagen Atomics is a startup in Copenhagen developing thorium reactors that use molten salt and will need lithium-7. —Katie Fehrenbacher, Axios, 11 Dec. 2024

But first, researchers needed to pinpoint the exact amount of energy capable of exciting the thorium nucleus. —Shi En Kim, Smithsonian Magazine, 23 Sep. 2024

Word History

Etymology

New Latin, from Old Norse Thōrr Thor

First Known Use

1832, in the meaning defined above

Rhymes for thorium

• fusarium
• solarium
• terrarium

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