ra·di·o (r??d?-?) 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.] American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.radio (?re?d???) n, pl -os1. (Telecommunications) the use of electromagnetic waves, lying in the radio-frequency range, for broadcasting, two-way communications, etc2. (Broadcasting) Also called (esp Brit): wireless an electronic device designed to receive, demodulate, and amplify radio signals from sound broadcasting stations, etc3. (Broadcasting) a similar device permitting both transmission and reception of radio signals for two-way communications4. (Broadcasting) the broadcasting, content, etc, of sound radio programmes: he thinks radio is poor these days. 5. (Broadcasting) a. the occupation or profession concerned with any aspect of the broadcasting of sound radio programmes: he’s in radio. b. (modifier) relating to, produced for, or transmitted by sound radio: radio drama. 6. (Telecommunications) short for radiotelegraph, radiotelegraphy, radiotelephone7. (Telecommunications) (modifier) a. of, relating to, employed in, or sent by radio signals: a radio station. b. of, concerned with, using, or operated by radio frequencies: radio spectrum. 8. (Automotive Engineering) (modifier) (of a motor vehicle) equipped with a radio for communication: radio car. vb, -os, -oing or -oed (Telecommunications) to transmit (a message) to (a person, radio station, etc) by means of radio waves[C20: short for radiotelegraphy]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ra?di?o (?re? di?o?) n., pl. -di?os, n. 1. a system of telecommunication employing electromagnetic waves of a particular frequency range to transmit speech or other sound over long distances without the use of wires. 2. an apparatus for receiving or transmitting radio broadcasts. 3. a message transmitted by radio. adj. 4. pertaining to, used in, or sent by radio. 5. pertaining to electromagnetic radiation having frequencies in the range of approximately 10 kHz to 300,000 MHz: radio waves. v.t. 6. to transmit (a message, music, etc.) by radio. 7. to send a message to (a person) by radio. v.i. 8. to transmit a message, music, etc., by radio. [1910?15; shortening of radiotelegraph or radiotelegraphy] radio- a combining form with the meanings ?radiant energy? (radiometer), ?radio waves? (radiophotograph ), ?emission of rays as a result of the breakup of atomic nuclei? (radioactivity), ?x-rays? (radiotherapy). [