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
A7(b9)
Alternative symbol
A7b9
Type
Pentad (five-note chord)

Ab7(b9) chord on piano

Ab7(b9) chord on guitar

Ab7(b9) chord on ukulele

Ab7(b9) chord on the staff