sesquitertia

English

Noun

sesquitertia (countable and uncountable, plural sesquitertias)

1. (obsolete) A ratio of 4 to 3.
   • 1570, John Dee, in H. Billingsley (trans.) Euclid, Elements of Geometry, Preface:

     For, what proportion, 100 hath to 75: the same hath 17 1/7 to 12 6/7: Which is Sesquitertia: that is, as 4, to 3. which make 7.

2. (music, obsolete) A perfect fourth, an interval having the ratio of 1 to 1⅓, or 3 to 4.