The F dominant seventh flat five chord (abbreviated "F7(b5) chord") is a four-note chord consisting of the notes F, A, C♭, and E♭. The chord is formed by lowering the fifth of a F dominant seventh chord a half step.
F dominant seventh flat five chord
F A C♭ E♭
1 3 ♭5 ♭7
Tetrad (four-note chord)