discord
A harsh, unpleasant combination of sounds; extreme dissonance.
In Depth
Discord (or discordance) describes a combination of sounds that is jarring, clashing, and unresolved. While dissonance is a broader term encompassing varying degrees of tension, discord implies an extreme, deliberately harsh quality that goes beyond normal musical tension.
In practice, what sounds discordant changes with context and expectation. Stravinsky's Rite of Spring sounded discordant to 1913 audiences but is now performed regularly without raising an eyebrow. Free jazz and noise music deliberately embrace discord as an expressive tool. The distinction between creative discord and mere cacophony lies in intention and context.
The premiere of Stravinsky's Rite of Spring in 1913 caused a near-riot — the audience found the music so discordant that they shouted, hissed, and eventually came to blows.