3645/3584
The aberdiesis[idiosyncratic term] or schismean comma[idiosyncratic term] (monzo: [-9 6 1 -1⟩, ratio: 3645/3584) is a small 7-limit comma measuring about 29.2 cents.
| Interval information |
schismean comma[idiosyncratic term]
It is the difference between three major whole tones and a small septimal tritone, or in other words, (9/8)3/(7/5).
Temperaments
It is most notably and characteristically tempered out in septimal meantone, where 7/5 is an augmented fourth, as the flat fifth of meantone helps motivate this equivalence.
Tempering out this comma leads to the rank-3 schismean temperament. Other rank-2 temperaments which temper out this comma include schism and pycnic.
Etymology
The name schismean was given by Xenllium in 2022, most likely as a contraction of schism and meantone. The name aberdiesis was given later in 2026 by the observation of Fumica to observe a pun with the closely-related comma (10/7)/(9/8)3 = S8/S9 = 5120/5103, the aberschisma, in light of Godtone's observation that it behaves in almost all ways like a diesis according to a specific intuitively-motivated definition discussed in Diesis#Generalization.