1. Any music or chord that contains notes not belonging to the diatonic scale.
2. Music which proceeds in half steps.

SUGGESTED LISTENING EXAMPLES:

Chromatic dissonance:
Wagner: Tristan und Isolde, Prelude

W. W. Norton - 4-CD Musical Example Bank -- Disc 3, Track 29

Chromatic harmony:
Bach: Chromatic Fantasia and Fugue in D minor, BWV 903 (opening of the fugue)

W. W. Norton - 4-CD Musical Example Bank -- Disc 1, Track 17

Bozza: Scherzo for Woodwind Quartet, Op. 48

W. W. Norton - 4-CD Musical Example Bank -- Disc 2, Track 1

Wagner: Tristan und Isolde, Prelude

W. W. Norton - 4-CD Musical Example Bank -- Disc 3, Track 29