Extended chord

Extended chords are tertian chords (built from thirds) or triads with notes extended, or added, beyond the seventh, including all the thirds in between the seventh and the extended note. Thus ninth, eleventh, thirteenth, and all farther chords are extended chords. Without the intervening thirds these chords become added note chords. Since all extended chords are based on compound intervals, some of the added tone chord names may be according to the compound number, thus an "added thirteenth chord" is really an added sixth or sixth chord.

When playing extended chords on instruments which are limited to four or less tones it is important to select which notes to play so as to still give the sonority or effect as the intended extended chord. Always play the root, third, seventh, and the most extended note if possible. The root is the central note of the chord, the third defines the chord's quality as minor or major, the extended note is what makes the chord extended, and the seventh defines the chord as an extended chord and not an added note chord. Any notes which happen to be altered, such as a flatted ninth, would also need to be included. Thus in a thirteenth chord one would play the root, third, seventh, and thirteenth, and be able to leave out the fifth, ninth, and eleventh.