The A-flat dominant seventh flat five chord (abbreviated "Ab7(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 dominant seventh chord a half step.
A-flat dominant seventh flat five chord
A♭ C E♭♭ G♭
1 3 ♭5 ♭7
Tetrad (four-note chord)