sesquĭ-octāvus, a, um, num. adj., corresp. to the Gr. ἐπόγδοος,
containing nine eighths , or one and an eighth; bearing the ratio of nine to eight : intervallum, Cic. Univ. 7, 21; cf. sesquitertius, and v. sesqui.
sēsqui-octāvus adj. num, containing nine eighths, one and an eighth: intervallum. ...
An Elementary Latin Dictionary