Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. interpŏsĭtus, a, um, P. a., v. interpono fin.
2. interpŏsĭtus, ūs, m. (only in abl. sing.), a putting between, interposition (rare but class.): luna interpositu interjectuque terrae repente deficit, Cic. N. D. 2, 40, 103: solis radios luna interpositu suo auferens terrae, Plin. 2, 10, 7, § 47.