Cm9 chord for piano with keyboard diagram.
Explanation: The C minor ninth is a five-note chord. For practical reasons the chord is normally played with omitted notes and/or inverted. The chord is often abbreviated as Cm9 (alternatively Cmin9).
Omissions: Cm9(no3): C - G - Bb - D; Cm9(no5): C - Eb - Bb - D.
Theory: The Cm9 chord is constructed with a root, a minor third, a perfect fifth, a minor seventh and a major ninth.