Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† Porthmeus (dissyl.), ĕi and ĕos, m., = Πορθμεύς, the ferryman, a name given to Charon (poet.): navita Porthmeus, Petr. 121.
Acc. Porthmea, Juv. 3, 266.