The B half-diminished seventh chord (abbreviated "Bm7(b5) chord") is a four-note chord consisting of the notes B, D, F, and A. The chord is formed by lowering the fifth of a B minor seventh chord a half step.
B half-diminished seventh chord
B half-diminished chord B minor seventh flat five chord
B D F A
1 ♭3 ♭5 ♭7
Bø Bø7 Bm7b5 B–7(b5) Bmi7(b5) Bmin7(b5)
Tetrad (four-note chord)