Euzenius comma
The euzenius comma is a 7-limit unnoticeable comma with a ratio of 78125000/78121827, a monzo of [3 -13 10 -2⟩, and a size of 0.070314 cents. It is the difference between two 6250/5103 intervals and the perfect fifth. It is tempered out in temperaments such as ennealimmal and fortune.
Temperament
Tempering this comma out gives euzenius temperament (→ Very high accuracy temperaments #Euzenius or Sabiruquinyo).