1 [noncount] : the system or process that is used for sending and receiving signals through the air without using wires
▪ The news was sent/received by/over radio. — often used before another noun ▪ radio communications/signals 2 [noncount] : programs that are broadcast by radio
▪ I listen to the radio all the time. ▪ I heard the news/song on the radio. — often used before another noun ▪ radio programs/shows/stations — see also talk radio 3 [count] a : a device that is used to receive the signals that are broadcast by radio
▪ There's a problem with the car's radio. ▪ a portable/transistor radio ▪ The radio was playing very loudly. ▪ Turn up/down/on/off the radio.
b : a device that is used to send and receive messages by radio
▪ two-way radios ▪ The pilot's radio wasn't working. 4 [noncount] : the business that makes and broadcasts radio programs
▪ He became the most popular talk show host in radio. ▪ She is a powerful force in radio.