C m(add9) Chord
How the C m(add9) chord is built: its notes, its interval structure, and where it fits.
The C m(add9) chord contains 4 notes: C – D – D# – G. It belongs to the ninth & extended 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.