You've never heard of hemiola??
The Harvard Dictionary of Music Fourth Edition edited by Don Randel describes hemiola as the ratio 3:2. This ratio can be used to describe rhythm or pitch. When referring to rhythm, hemiola refers to the use of three notes of equal value in the time normally occupied by two notes of equal value. This rhythm was commonly used in the music of 15th century composers, French Baroque, African and Mid-eastern music, and the music of Brahms and Schumann. In terms of pitch, hemiola is the ratio of the lengths of two strings, when played together, sound like a perfect fifth.