C major sharp eleventh (lydian) piano chord - Cmaj9#11
The C major sharp eleventh (lydian) chord is a 6-note chord consisting of the notes C, E, G, B, D and F#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Cmaj9#11.
Interactive piano diagram for the C major sharp eleventh (lydian) chord
Chords that are a subset of Cmaj9#11. These contain less notes but all of them are included in Cmaj9#11.