(plural CB radios)
For Citizens' Band.
(Citizen's Band radio) The frequency band of 40 channels for public radio transmission in the 27 MHz range. CB radio uses the same frequencies for sending and receiving on each channel, which is why only one person can talk at the same time (half duplex transmission). With a range of approximately five miles, CB radios were popular with truck drivers in the 1970s and 1980s until mostly giving way to cellphones. See ISM band.