Extended chord

In music, extended chords are tertian chords with notes beyond the seventh. Chords such as the Ninth, eleventh, and thirteenth chords are extended chords. The thirteenth is the furthest extension diatonically possible as, by that point, all seven tonal degrees are represented within the chord. In practice, however, extended chords do not typically use all the chord members: the fifth is often omitted, as well as the ninth and eleventh, unless they are altered to give a special texture.