C Dominant 9th
9
0 - 4 - 7 - 10 - 14Dom7 + major 9th
About C Dominant 9th
C9 is a dominant seventh with a ninth stacked on top: C, E, G, B♭ and D. Five notes on six strings means something has to give, and on guitar it is usually the fifth — which nobody misses, because the ninth carries the colour and the seventh carries the pull.
The notes
C, E, G, B♭, D. The B♭ makes it a dominant; the D is the ninth, an octave above the second degree of the scale. Together they give the chord its characteristic sound: unresolved, but far warmer than a plain seventh.
In practice the G is dropped. Four notes — root, third, seventh, ninth — carry everything the chord needs, and the omission frees a finger.
The shape that everyone uses
The standard ninth voicing sits on the middle four strings with the root on the A string, and it is movable: the same fingering at the third fret gives C9, at the fifth D9, at the eighth F9. Learning it once covers every key.
It is one of the few chord shapes that funk and soul rhythm playing genuinely requires — the sound of a muted, percussive ninth is the genre itself.
Where it shows up
Blues, funk and soul above all. A twelve-bar in F played with ninths instead of sevenths turns immediately from folk blues into something urban.
In jazz it serves as the V of a ii–V–I, where the ninth softens the dominant without weakening its pull. C9 to F is the same motion as C7 to F, with better manners.