Fbmaj11 chord

The F-flat major eleventh chord (abbreviated Fbmaj11 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 major ninth chord.

In practice, the fifth (C♭) is often omitted from the Fbmaj11 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.