The D half-diminished seventh chord (abbreviated "Dm7(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 minor seventh chord a half step.
D half-diminished seventh chord
D half-diminished chord D minor seventh flat five chord
D F A♭ C
1 ♭3 ♭5 ♭7
Dø Dø7 Dm7b5 D–7(b5) Dmi7(b5) Dmin7(b5)
Tetrad (four-note chord)