Harsh or unpleasant sound.
To some people, much recent jazz sounds more like cacophony than like real music.
Cacophony employs the Greek prefix caco-, meaning "bad," but not everything we call cacophonous is necessarily bad. Open-air food markets may be marked by a cacophony of voices but also by wonderful sights and sounds. Heavy metal is probably the most cacophonous form of modern music but it is still very popular. On the other hand, few people can really enjoy, for more than a few minutes, the cacophony of jackhammers, car horns, and truck engines that assaults the city pedestrian on a hot day in August.