boombox UK /ˈbuːm.bɒks/US /ˈbum.bɑks/ noun1 •A powerful portable audio system for listening collectively to recorded or broadcast sound.Bluebeat and ska from a boombox on the pavement. A suedehead dancing a delirious, inebriated moonstomp with a girl who looked like a solicitor's apprentice. — 2013 formsboomboxes