radiothorium

noun

ra·​dio·​tho·​ri·​um ˌrā-dē-ō-ˈthȯr-ē-əm How to pronounce radiothorium (audio)
: a radioactive isotope of thorium with the mass number 228

Word History

Etymology

New Latin

First Known Use

1905, in the meaning defined above

Time Traveler
The first known use of radiothorium was in 1905

Rhymes for radiothorium

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Browse Nearby Words

radiothermics
radiothorium
radiotracer
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Cite this Entry

“Radiothorium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radiothorium. Accessed 7 Jul. 2026.

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Medical Definition

radiothorium

noun
ra·​dio·​tho·​ri·​um -ˈthōr-ē-əm, -ˈthȯr- How to pronounce radiothorium (audio)
: a radioactive isotope of thorium with the mass number 228

More from Merriam-Webster on radiothorium

Britannica.com: Encyclopedia article about radiothorium

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