Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Āsōpus (-os), i, m. (nom. Gr. Asopos, Stat. Th. 7, 315; acc. Gr. Asopon, Ov. Am. 3, 6, 33), = Ἀσωπός.