Lewis & Short

Dānŭvĭus (the ending -ubius is a corruption of late Latin, Corss. Ausspr. 1, 126), ii, m., Δανούβιος,

  1. I. the Danube (in the upper part of its course; in the lower called Ister, though the poets use both names promiscuously), Mel. 2, 1, 8; Plin. 4, 12, 25, § 80; Amm. 22, 9; * Caes. B. G. 6, 25; Sall. H. Fragm. ap. Acr. Hor. A. P. 18 (3, 9 Dietsch); Tac. G. 29; Ov. Pont. 4, 9, 80; id. Tr. 2, 192 al.; Hor. Od. 4, 15, 21; Tac. G. 1; id. A. 2, 53; Orell. Inscr. 648 al.
    Hence,
  2. II. Dānŭvīnus (Danub-), a, um, adj., of or belonging to the Danube, Danubian: limes, Sid. Ep. 8, 12.