(uncountable) The technology that allows for the transmission of sound or other signals by modulation of electromagnetic waves.

(countable) A device that can capture (receive) the signal sent over radio waves and render the modulated signal as sound.

(countable) On-board entertainment system in a car, usually including a radio receiver as well as the capability to play audio from recorded media.

(countable) A device that can transmit radio signals.

(Internet, uncountable) The continuous broadcasting of sound via the Internet in the style of traditional radio.

(transitive, intransitive) To use two-way radio to transmit (a message) (to another radio or other radio operator).

(transitive) To order or assist (to a location), using telecommunications.