Fbm11 chord

The F-flat minor eleventh chord (abbreviated Fbm11 chord) is a six-note chord consisting of the notes F♭, A♭♭, C♭, E♭♭, G♭, and B♭♭. The chord is formed by adding an eleventh to the F-flat minor ninth chord.

In practice, the fifth (C♭) is often omitted from the Fbm11 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.