F 9#11 Chord
How the F 9#11 chord is built: its notes, its interval structure, and where it fits.
The F 9#11 chord contains 5 notes: F – G – A – B – D#. It belongs to the sharp 11 (lydian) family of chord qualities. Like every chord, it is defined by the distances (intervals) between its notes, not by any one instrument — which is why the same formula names the chord whether it is voiced on a fretboard, a keyboard, or a choir.