C Major 11th Chord
C Major 11th is built from the notes C, D, E, F, G, B. The interval from C to D is a major 2nd (2 semitones), from C to E is a major 3rd (4 semitones), from C to F is a perfect 4th (5 semitones), from C to G is a perfect 5th (7 semitones), from C to B is a major 7th (11 semitones).
The major 11th is tricky territory — the perfect 11th clashes harshly with the major 3rd. In practice, it's usually played with the 3rd removed, or the 11th is raised to ♯11 (which becomes a different chord). It's more of an atmospheric texture than a standard functional chord.
The theoretical formula is R, 3, 5, 7, 9, 11, but the 11th sits a minor 9th above the 3rd — one of the most dissonant intervals. In standard harmony, the natural 11th is treated as an "avoid note" on major chords. When guitarists or arrangers want an 11th on a major chord, they almost always raise it to ♯11 (Lydian sound) or omit the 3rd entirely.
If you play this chord, you're likely either omitting the 3rd (making it a stack of 4ths) or using it as a brief passing voicing. The shape works in modal and ambient contexts where conventional rules are relaxed. Think of it as a texture rather than a functional chord.