Ab7(b9) chord
The A-flat dominant minor ninth chord (abbreviated "Ab7(b9) chord") is a five-note chord consisting of the notes A♭, C, E♭, G♭, and B♭♭. The chord is formed by adding a major ninth to a A-flat dominant seventh chord.
In practice, the fifth (E♭) is often omitted from the Ab7(b9) chord because it's not always possible to play all notes simultaneously.
Name
A-flat dominant minor ninth chord
Notes
A♭ C E♭ G♭ B♭♭
Intervals
1 3 5 ♭7 ♭9
Chord symbol
A♭7(b9)
Alternative symbol
A♭7b9
Type
Pentad (five-note chord)