thoriumn. 釷釷Th學術名詞釷：化學元素、地球科學、電機工程、礦冶工程、材料科學、金屬材料釷Th：電力工程英文釋義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