/dis"euh neuhns/ , n.
1. inharmonious or harsh sound; discord; cacophony.
2. Music.
a. a simultaneous combination of tones conventionally accepted as being in a state of unrest and needing completion.
b. an unresolved, discordant chord or interval. Cf. consonance (def. 3). See illus. under resolution .
3. disagreement or incongruity.
[ 1565-75; dissonantia, equiv. to disson- (see DISSONANT) + -antia -ANCE ]