Definition of Pythagorean comma in English:

Pythagorean comma

noun

Music
  • The difference in pitch between twelve intervals of a perfect pitch above a given note and seven octaves above the same note; an interval of this size.

    The ratio of the two frequencies is 531441:524288, or 312:219.

Origin

Late 18th century; earliest use found in John Keeble (1711–1786), organist.