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[rey-dee-oh] /ˈreɪ diˌoʊ/
noun, plural radios.
wireless telegraphy or telephony:
speeches broadcast by radio.
an apparatus for receiving or transmitting radio broadcasts.
a message transmitted by radio.
pertaining to, used in, or sent by radio.
pertaining to or employing radiations, as of electrical energy.
verb (used with object), radioed, radioing.
to transmit (a message, music, etc.) by radio.
to send a message to (a person) by radio.
verb (used without object), radioed, radioing.
to transmit a message, music, etc., by radio.
Origin of radio
1910-15; shortening of radiotelegraph or radiotelegraphy
Related forms
preradio, adjective


a combining form with the meanings “dealing with radiant energy” (radiometer), “employing or dealing with radio waves” (radioacoustics; radiolocation; radiotelephone), “emitting rays as a result of the breakup of atomic nuclei” (radioactive; radiocarbon), “characterized by, employing or dealing with such rays” (radiography; radiopaque; radiotherapy).
< French, combining form representing Latin radius beam, ray, radius Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for radio
Contemporary Examples
Historical Examples
  • All the while the radio beacon signal was buzzing loudly in his ears.

    The Flying Reporter Lewis E. (Lewis Edwin) Theiss
  • He contacted the Operations people in the bunker over the radio net.

    Next Door, Next World Robert Donald Locke
  • There were three in the gang and they got him and the radio paper which was stolen from our file.

  • "We'd better get them on the radio," said Jones, turning back toward the ship.

    The Dope on Mars John Michael Sharkey
  • This undeserved insult was more than the radio boys could stand, and all stepped forward with clenched fists.

British Dictionary definitions for radio


noun (pl) -os
the use of electromagnetic waves, lying in the radio-frequency range, for broadcasting, two-way communications, etc
Also called (esp Brit) wireless. an electronic device designed to receive, demodulate, and amplify radio signals from sound broadcasting stations, etc
a similar device permitting both transmission and reception of radio signals for two-way communications
the broadcasting, content, etc, of sound radio programmes: he thinks radio is poor these days
  1. the occupation or profession concerned with any aspect of the broadcasting of sound radio programmes: he's in radio
  2. (modifier) relating to, produced for, or transmitted by sound radio: radio drama
  1. of, relating to, employed in, or sent by radio signals: a radio station
  2. of, concerned with, using, or operated by radio frequencies: radio spectrum
(modifier) (of a motor vehicle) equipped with a radio for communication: radio car
verb -os, -oing, -oed
to transmit (a message) to (a person, radio station, etc) by means of radio waves
Word Origin
C20: short for radiotelegraphy


combining form
denoting radio, broadcasting, or radio frequency: radiogram
indicating radioactivity or radiation: radiochemistry, radiolucent
indicating a radioactive isotope or substance: radioactinium, radiothorium, radioelement
Word Origin
from French, from Latin radius ray; see radius
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for radio

"wireless transmission of voice signals with radio waves," 1907, abstracted from earlier combinations such as radio-receiver (1903), radiophone (1881), radio-telegraphy (1898), from radio- as a comb. form of Latin radius "beam." Use for "radio receiver" is first attested 1913; sense of "sound broadcasting as a medium" is from 1913.

It is not a dream, but a probability that the radio will demolish blocs, cut the strings of red tape, actuate the voice "back home," dismantle politics and entrench the nation's executive in a position of power unlike that within the grasp of any executive in the world's history. ["The Reading Eagle," Reading, Pa., U.S.A., March 16, 1924]
Wireless remained more widespread until World War II, when military preference for radio turned the tables. As an adjective by 1912, "by radio transmission;" meaning "controlled by radio" from 1974. Radio _______ "radio station or service from _______" is recorded from 1920. A radio shack (1946) was a small building housing radio equipment.


1916, from radio (n.). Related: Radioed; radioing.


word-forming element meaning 1. "ray, ray-like" (see radius); 2. "radial, radially" (see radial (adj.)); 3. "by means of radiant energy" (see radiate (v.)); 4. "radioactive" (see radioactive); 5. "by radio" (see radio (n.)).

Online Etymology Dictionary, © 2010 Douglas Harper
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radio in Medicine

radio- or radi-

  1. Radiation; radiant energy: radiometer.

  2. Radioactive: radiochemistry.

  3. Radius: radiobicipital.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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radio in Science
Noun  The equipment used to generate, alter, transmit, and receive radio waves so that they carry information.

Adjective  Relating to or involving the emission of radio waves.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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