ra·di·o 
(rādē-ō)
(rādē-ō)n. pl. ra·di·os
1. Electromagnetic radiation with lower frequencies and longer wavelengths than those of microwaves, having frequencies lower than 300 megahertz and wavelengths longer than 1 meter.
2.
a. The transmission and reception of electromagnetic waves within this range, especially when convertible to audible sounds: the use of radio in warfare.
b. A device, such as a walkie-talkie, that transmits or receives such signals.
3.
a. The system or industry that broadcasts programs of audio content to the public or subscribers by means of radio waves or over the internet: She was famous during the early days of radio.
b. Audio content, especially short programs or sets of songs, created for or distributed through such a system: listening to radio.
c. An electronic device for listening to radio programming, consisting of a tuner and speakers.
v. ra·di·oed, ra·di·o·ing, ra·di·os
v. tr.
1. To transmit by radio: radio a message to headquarters.
2. To transmit a message to by radio: radioed the spacecraft.
v. intr.
To transmit messages or a message by radio: a ship radioing for help.
[Short for RADIOTELEGRAPHY.]