A tredezime (more rarely: "Tredezim", from Latin tredecimus : "the thirteenth") or third decime is an interval in music that is made up of an octave and a sixth and thus spans thirteen notes of a diatonic , heptatonic scale (e.g. B. c-a ' ). The large tredezime (a) comprises 21 semitones, the small tredezime (b) 20 semitones. Example (c) shows a tredezima chord obtained by layering thirds .
Note example: three-decimal intervals
The term is also applicable when the interval spans a sixth and two or more octaves. Usually it is only used to emphasize the additional octave distance between the root and the sixth. Otherwise the term “sixth” is preferable.
Furthermore, the tredezime in the jazz harmonic is the sixth third above the root (c) and is numbered as “13” in the chord symbolism.