The C added ninth chord (abbreviated "Cadd9 chord") is a four-note chord consisting of the notes C, E, G, and D. The chord is formed by adding a major ninth to a C major chord.

Often, a major second is played instead of the major ninth since they are the same note.

Name
C added ninth chord
Synonym
C added second chord
Notes
C E G D
Intervals
1 3 5 9
Chord symbol
Cadd9
Alternative symbols
C(add9) Cadd2 C(add2)
Type
Tetrad (four-note chord)

Cadd9 chord on piano

Cadd9 chord on guitar

Cadd9 chord on ukulele

Cadd9 chord on the staff