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