The wireless transmission through space of electromagnetic waves in the approximate frequency range from 10 kilohertz to 300,000 megahertz. Communication of audible signals encoded in electromagnetic waves. Transmission of programs for the public by radio broadcast. An apparatus used to transmit radio signals; a transmitter. An apparatus used to receive radio signals; a receiver. A complex of equipment capable of transmitting and receiving radio signals. A station for radio transmitting. A radio broadcasting organization or network of affiliated organizations. The radio broadcasting industry. A message sent by radio. To transmit by radio: radio a message to headquarters. To transmit a message to by radio: radioed the spacecraft. To transmit messages or a message by radio: a ship radioing for help.