ˈɹeɪdiˌəʊ ˈɹeɪdiˌoʊ ˈɹeɪdiˌəʊ ˈɹeɪdiˌoʊ ˈwaɪə.ləs ˈwaɪ(ə)ɹ.ləs transmit messages via radio waves he radioed for help indicating radiation or radioactivity radiochemistry a communication system based on broadcasting electromagnetic waves an electronic receiver that detects and demodulates and amplifies transmitted signals medium for communication