Lewis & Short

Aufĭdus, i, m., = Αὔφιδος, a river in Apulia, remarkable for its swift and violent course, now Ofanto: longe sonans, Hor. C. 4, 9, 2: violens, id. ib. 3, 30, 10: acer, id. S. 1, 1, 58; on account of its divided outlet: tauriformis, id. C. 4, 14, 25; cf. Mann. Ital. II. p. 30 sq.
Hence, Aufĭ-dus, a, um, adj., of Aufidus: stagna, Sil. 10, 171.