The A dominant seventh flat five chord (abbreviated "A7(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 dominant seventh chord a half step.
A dominant seventh flat five chord
A C♯ E♭ G
1 3 ♭5 ♭7
Tetrad (four-note chord)