B#11 chord

The B-sharp dominant eleventh chord (abbreviated B#11 chord) is a six-note chord consisting of the notes B♯, D, F, A♯, C, and E♯. The chord is formed by adding an eleventh to the B-sharp dominant ninth chord.

In practice, the third (D) and fifth (F) are often omitted from the B#11 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.