O
| English Name | Other name(s) or older name(s) |
|---|---|
| Oder | Oder (French, German, Dutch, Italian, Portuguese, Spanish, Swedish, Turkish), Òder (Catalan), Odera (Hungarian), Odera or Oddera (medieval Latin), Odra (Bosnian, Croatian, Czech, Estonian, Polish, Romanian, Slovak, Slovene), Viadua, Viadrua, or Viadrus (Latin), Viadros - Βιαδρος (Ancient Greek) |
| Ohře | Eger (German), Ohrza (Polish), Ohře (Czech) |
| Olt | Aluta (Polish), Alutus (Latin), Olt (Hungarian, Romanian), Alt (German), Alytos - Αλυτος (Greek) |
| Olza | Olsa (German), Olša (Slovak), Olše (Czech), Olza (Polish) |
| Orava | Arva (Latin), Árva (Hungarian), Arwa (German), Orava (Czech, Slovak), Orawa (Polish) |
| Oulujoki | Oulujoki (Finnish), Ule älv (Norwegian, Swedish) |
| Ourthe | Ourte (former French ), Ourthe (French), Oûte (Walloon) |
Read more about this topic: List Of European Rivers With Alternative Names