1 in ancient Greek music : quarter tone
2 : the difference between three conjunct major thirds and an octave (ratio 125:128) https://www.merriam-webster.com/dictionary/enharmonic%20diesis]
See Also
Diesis
Enharmonic
Enharmonic Sixth
enharmonic third
Interval
11.18 - Keelys Dominant - Harmonic and Enharmonic
14.22.1 - Enharmonic is the High Neutral
9.24 - Elliptical Enharmonic Orbit