Viadus
Οὐίαο͂ος
Viadus (Οὐίαο͂ος), a river of Germany, west of the Vistula, mentioned by both Ptolemy (2.11.2) and Marcianus (p. 53) as flowing into the Mare Suevicum or Baltic. Neither of these authors mentions either its source or its course, but it is generally assumed to be the Oder. Ptolemy in another passage (2.11.15) mentions, according to the common reading, a river Ἰαδούα, which some regard as a tributary of the Viadus, and others as a name of the upper Viadus; but Wilberg, the latest editor of Ptolemy, treating Ἰαδούα as a corrupt reading, has altered it to Οὐίαδος.
From William Smith (ed.), Dictionary of Greek and Roman Geography. Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities and Tufts University. Data accessed from https://github.com/PerseusDL/canonical-pdlrefwk/ on 17 October 2026.