Half-Diminished (m7♭5)

Typical ii in minor

Prove it — just do the practice exercise.
Bm7b5 Root Position
B (R)D (♭3)F (♭5)A (♭7)
The half-diminished chord (ø7):

• R – ♭3 – ♭5 – ♭7

Like m7, but with diminished 5th. Essential in minor ii-V-I
(e.g. Bø7 → E7 → Am).

Example: Bm7♭5 = B + D + F + A