B sixth/ninth chord
B6/9 chord for piano with keyboard diagram.
Explanation: The B sixth/ninth is a five note chord. Due to practical circumstances, however, the fifth (F#) is often omitted and/or the chord is played inverted. The chord is abbreviated B6/9.
Theory: The B6/9 chord is constructed with a root, a major third, a perfect fifth, a major sixth and a major ninth.
Notes: B - D# - F# - G# - C#