cb radio

from The Collaborative International Dictionary of English v.0.48

CB \CB\ n.
   same as {citizens' band}; that portion of the radio frequency
   spectrum allocated by the FCC for the use of individual
   citizens for short-distance personal or business use, from
   either fixed or mobile stations. Also used attributively, as

   {CB radio}. [acronym]

   Syn: Citizens' Band.
        [PJC]