| Component intervals from root | |
|---|---|
| major seventh | |
| diminished fifth (tritone) | |
| minor third | |
| root | |
| Forte no. / | |
| 4-18 / |
In music theory, a diminished major seventh chord is a seventh chord composed of a diminished triad and a major seventh.[1] Thus, it is composed of a root note, together with a minor third, a diminished fifth, and a major seventh above the root: (1, ♭3, ♭5, 7). For example, the diminished major seventh chord built on C, commonly written as CoM7, has pitches C–E♭–G♭–B:
Diminished major seventh chords are very dissonant, containing the dissonant intervals of the tritone and the major seventh. They are frequently encountered, especially in jazz, as a diminished seventh chord with an appoggiatura, especially when the melody has the leading note of the given chord: the ability to resolve this dissonance smoothly to a diatonic triad with the same root allows it to be used as a temporary tension before tonic resolution. It is nevertheless infrequently used as a chord in itself.
The chord can be represented by the integer notation {0, 3, 6, 11}.
