Lewis & Short

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

1. Marpessus or Marpēsus, i, f., = Μάρπησσος (another form of Μάρμησσος v. Marmessus), a town in the Troas, on Mount Ida, home of the Erythrean Sibyl, Varr. ap. Lact. 1, 6, 12.
Hence, adj.: Marpessĭus (-ēsius), a, um, of or belonging to Marpessus in the Troas, Marpessian, Tib. 2, 5, 67 Drisen.

2. Marpessus (Marpēsus), i, m., = Μάρπησσος, a mountain in the island of Paros, in which lay the quarries of Parian marble, Serv. Verg. A. 6, 471.
Hence, Marpessĭus (Marpēsĭus), a, um, adj., of or belonging to Marpessus in Paros, Marpessian; and transf., Parian: Marpessia cautes, i. e. Parian, Verg. A. 6, 471; and referring to the above passage, Marpessia rupes, Arn. 2, 60.