The A-flat half-diminished seventh chord (abbreviated "Abm7(b5) chord") is a four-note chord consisting of the notes A♭, C♭, E♭♭, and G♭. The chord is formed by lowering the fifth of a A-flat minor seventh chord a half step.
A-flat half-diminished seventh chord
A-flat half-diminished chord A-flat minor seventh flat five chord
A♭ C♭ E♭♭ G♭
1 ♭3 ♭5 ♭7
A♭ø A♭ø7 A♭m7b5 A♭–7(b5) A♭mi7(b5) A♭min7(b5)
tetrad (four-note chord)