(rā′dē·ō) noun plural ·os
1. The science, art, and process of communicating by means of radiant energy transmitted directly through space in waves.
2. The wireless transmission of radio waves within assigned frequencies and their reception by devices adapted for reconverting the frequencies into their corresponding original signals.
3. A radio program or broadcast; also, the combined operations for its production.
4. A radio receiving set and its accessories.
5. A radio message or radiogram.
6. The exploitation and development of radio as a commercial enterprise; the radio business and industry.
—adjective
1. Of, pertaining to, designating, employing, or produced by radiant energy, especially in the form of electromagnetic waves: a radio beam.
2. Wireless.
—v.t. & v.i. To transmit (a message, etc.) or communicate with (someone) by radiotelegraphy or radiotelephony. [<RADIO(TELEGRAPHY)]

1. Anat. Radial; pertaining to the radius: radiodigital, of the fingers on the radial edge of the hand.
2. Radio; produced by or related to radio: radiogram.
3. Chem. Radioactive; of, produced by, or causing radioactivity: radioscope, radiothorium.
4. Med. Radiant energy; using radiant energy: radiotherapy. [<L radius a ray]