1 文書を見つけるための辞書。

• thorium, atomic number 90, th
• トリウム
• 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
• 柔らかで銀白色の4価の放射性金属元素