RADIO

• ra‧di‧o
• 1
• a) [countable] a piece of electronic equipment which you use to listen to programmes that are broadcast, such as music and news
• turn/switch the radio on/off
• I sat down and turned on the radio.
• b) [uncountable] programmes that are broadcast on the radio:
• I don't really listen to the radio very much.
• on the radio
• Did you hear the interview with the Prime Minister on the radio this morning?
• radio programme/show
• He's got his own radio show now.
• local/national radio
• She works for a local radio station.
• 2
• a) [countable] a piece of electronic equipment, for example on a plane or ship, which can send and receive spoken messages
• over the radio
• We received a call for help over the ship's radio.
• b) [uncountable] when messages are sent or received in this way
• by radio
• We should be able to reach them by radio.
• We've lost radio contact with the plane.

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.