thorium

noun tho·ri·um \ˈthȯr-ē-əm\

Definition of THORIUM

: a radioactive metallic element that is obtained especially from monazite and is usually associated with rare earths — see element table

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New Latin, from Old Norse Thōrr Thor

First Known Use: 1832

Medical Dictionary

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 element table

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