(uncountable) That part of the electromagnetic spectrum, between about 3 kHz and 300 MHz, within which radio waves are transmitted. / (countable) A frequency in this range.

A device designed to reflect radar waves well in order to make it clearly visible on radar screens. Radar reflectors can be installed for example in boats or signal buoys.

(physics) Any of several processes by which unstable nuclei emit subatomic particles and/or ionizing radiation and disintegrate into one or more smaller nuclei.

plural of radio beacon

(communication, aviation, nautical, navigation) A beacon that emits radio wave signals to guide ships or aircraft or to indicate the position of a ship, aircraft, or other object, person, or vehicle.

An alarm clock that includes a radio; a radio alarm clock

(physics) The energy transmitted by radio-frequency electromagnetic radiation

Any of a line of preset buttons on a car radio used to select the station to be listened to; pressing one releases the others

(astronomy) All the electromagnetic radiation entering the Earth from non-point sources in deep space.

(physics) electromagnetic radiation that has a frequency of about 3 to 30 GHz