Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* 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.