In
music,
extended chords are
tertian chords (built from
thirds) or
triads with notes
extended, or added, beyond the
seventh.
Ninth,
eleventh, and
thirteenth chords are extended chords. The thirteenth is the farthest
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; when it is not altered, the fifth is often omitted, as are notes between the seventh and the highest note (i.e., the ninth is often omitted in an eleventh chord; the ninth and eleventh are usually omitted in a thirteenth chord), unless they are altered to give a special texture. See
chord alteration.