(dated) A small portable radio receiver having transistors rather than thermionic valves; popular from the late 1950s.

Synonym of crystal set

(chiefly Britain, informal) Radio (sound broadcasting), considered as old-fashioned compared to television.

(astronomy) A device for observing astronomical sources of radio waves, normally having one or more large parabolic dishes.

(physics) electromagnetic radiation having a wavelength between about .5 centimeters and 30,000 meters; used for the broadcasting of radio and television signals.

Broadcasting without having the necessary license that covers the territory where the signals are received.

(colloquial) The hobby of amateur radio communication.

The hobby or pastime of communicating by two-way radio, often striving for “DX” QSOs that are challenging because of distance.

(medicine) A surgical instrument that uses a high-frequency electric arc to cut through or cut away tissue and at the same time sterilize the edges of the wound and seal cut blood vessels.

The location of a radio transmitter by taking bearings from two receivers. / The location of a vessel or aircraft by taking bearings to two transmitters of known position.