RADIOACTIVE Meaning of RADIOACTIVE in English radioactive BrE AmE ˌreɪd i‿əʊ ˈækt ɪv ◂ AmE \ ˌ••oʊ-▷ radioactive|ly li▶ ˌ radio ˌ active de ˈ cay BrE AmE Longman Pronunciation English Dictionary. Английский словарь произношений Longman. 2012