C#9 chord

The C-sharp dominant ninth chord (abbreviated C#9 chord) is a five-note chord consisting of the notes C♯, E♯, G♯, B, and D♯. The chord is formed by adding a major ninth to the C-sharp dominant seventh chord.

In practice, the fifth (G♯) is sometimes omitted from the C#9 chord because it's not always possible to play all notes simultaneously.