Bbm7b5 chord for piano with keyboard diagram.
Explanation: The B flat minor seventh flat five is also called B flat half-diminished (also written as Bbø). The chord is abbreviated Bbm7b5, Bbm7(b5) or Bbm7-b5.
Theory: The Bbm7b5 is a B flat minor seventh with a lowered fifth.
Notes: Bb - Db - E - Ab