Explanation: The A flat eleventh is a six-note chord. ... The chord is also often played inverted. The chord is abbreviated as Ab11. Omissions: Ab11(no3): Ab - Eb - Gb - Bb - Db; Ab11(no9): Ab - C - Eb - Gb - Db. Theory: The Ab eleventh chord is constructed by adding a third to a ninth chordninth chordIn music theory, a ninth chord is a chord that encompasses the interval of a ninth when arranged in close position with the root in the bass. The ninth chord and its inversions exist today, or at least they can exist.https://en.wikipedia.org › wiki › Ninth_chordNinth chord - Wikipedia.