Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* sesquĭ-tertĭus, a, um, num. adj., corresp. to the Gr. ἐπίτριτος, containing one and a third, or four thirds; bearing the ratio of four to three: intervallum, Cic. Univ. 7, 21; cf. sesquioctavus, and v. sesqui.