C sixth/ninth chord
C6/9 chord for piano with keyboard diagram.
Explanation: The C sixth/ninth is a five note chord. Due to practical circumstances, however, the fifth (G) is often omitted and/or the chord is played inverted. The chord is abbreviated C6/9.
Theory: The C6/9 chord is constructed with a root, a major third, a perfect fifth, a major sixth and a major ninth.
Notes: C - E - G - A - D