Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
2. Cispĭus (also Cespĭus, old form in Varr. L. L. 5, § 50 Müll.): mons, one of the peaks of the Mons Esquilinus, now the church S. Maria Maggiore, Varr. L. L. l. l.; Gell. 15, 1, 2; Fest. p. 348, 28; p. 351, 1; Paul. ex Fest. p. 42, 11; cf. Becker, Antiq. 1, p. 534 sq.