The D dominant seventh flat five chord (abbreviated "D7(b5) chord") is a four-note chord consisting of the notes D, F♯, A♭, and C. The chord is formed by lowering the fifth of a D dominant seventh chord a half step.
D dominant seventh flat five chord
D F♯ A♭ C
1 3 ♭5 ♭7
Tetrad (four-note chord)