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Noun: thorium  tho-ree-um
  1. A soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands
    - Th, atomic number 90

Derived forms: thoriums

Type of: metal, metallic element

Part of: monazite, thorite

Encyclopedia: Thorium