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

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

But making all that possible will require cutting down the uncertainty of thorium’s transition by at least another tenfold. —Shi En Kim, Smithsonian Magazine, 23 Sep. 2024

The team trained the laser comb onto thorium atoms embedded in calcium fluoride grains and scanned for the telltale frequency. —Shi En Kim, Smithsonian Magazine, 23 Sep. 2024

The thorium nuclear state’s energy is far more sensitive to variations in the fundamental constants than that of any atomic state. —Quanta Magazine, 4 Sep. 2024

Word History

Etymology

New Latin, from Old Norse Thōrr Thor

First Known Use

1832, in the meaning defined above

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