Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Pēnēus, i, m., = Πηνειός, a principal river in Thessaly, which rises in Mount Pindus, flows through the Vale of Tempe, and falls into the Gulf of Therma, the modern Selembria; in mythology, a rivergod, the father of Cyrene and Daphne, Ov. M. 1, 569 sq.; Plin. 4, 8, 15, § 31; Liv. 32, 15; Verg. G. 4, 355; Hyg. Fab. 161; 203.
Voc. Penee, Ov. Am. 3, 6, 31.
Hence,