A major ninth chord
Amaj9 chord for piano with keyboard diagram.
Explanation: The A major ninth is a five note chord and can be regarded as a Amaj7 with an added ninth. It is often abbreviated as Amaj9 (should not be confused with A9).
Theory: The Amaj9 chord is constructed with a root, a major third, a perfect fifth, a major seventh and a major ninth.
Notes: A - C# - E - G# - B