ra·dio·tho·ri·um /-ˈθoriəm, ˈθɔr-/
ra·dio·tho·ri·um /-ˈθorɪəm, ˈθɔr-/ 名詞 放射性釷,射釷
radiothorium n : radioactive isotope of thorium with mass number 228 [syn: thorium-228]