Radio, for one, is an electronic device used to transmit and receive sound signals through the air. It is a form of wireless communication that has been around since the late 19th century. RADIO is used for broadcasting music, news, and other forms of entertainment. It is also used for communication between two or more people, such as in walkie-talkies. The term 'RADIO' is derived from the Latin word 'RADIUS, ' which means 'RAY.' The SET solution for this crossword is RAD.