Thirteenth

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In music or music theory, a thirteenth is the note thirteen scale degrees from the root of a chord.

A thirteenth is a compound sixth (an octave plus a sixth).

A thirteenth chord is a tertian chord containing the interval of a thirteenth, and is an extended chord if it includes the ninth and the eleventh. A chord containing the interval of a thirteenth without the intervals of the ninth and eleventh are often called sixth chords.

In modern pop/jazz harmony, a thirteenth chord (usually notated as 13, e.g. C13) contains an implied flatted seventh interval. Thus, a C13 consists of C E G Bb and A. The underlying harmony during a thirteenth chord is usually Mixolydian or Lydian Dominant. A thirteenth chord does not imply the quality of the ninth or eleventh scale degrees. In general, what gives a thirteenth chord its characteristic sound is the dissonance between the dominant seventh and the thirteenth.

In rare cases, the seventh of such a chord may retain its diatonic (and therefore non-lowered) pitch, but when this is the case, the thirteenth chord will nearly always feature a chromatically raised eleventh.

Chords
By Type	Triads	Major · Minor · Augmented · Diminished
	Sevenths	Major · Minor · Dominant · Diminished · Half-diminished · Minor-Major · Augmented major · Augmented minor
	Extended	Ninth · Eleventh · Thirteenth
	Other	Sixth · Augmented sixth · Suspended · Altered · Added tone · Polychord · Quartal and quintal · Tone cluster
By Function	Diatonic	Tonic · Dominant · Subdominant · Submediant
	Altered	Borrowed · Neopolitan sixth · Secondary dominant · Secondary subdominant