O
| English name | Other names or former names |
|---|---|
| Obwalden | Obvaldo (Italian), Obwald (French), Obwalden (Dutch, Estonian, German, Swedish) |
| Öland | Elandas (Lithuanian), Oelande (French), Oelandia (Latin), Öland (Estonian, Swedish), Øland (Danish), Olandia (Polish), Öölanti (Finnish) |
| Orava | Arva (Latin), Árva (Hungarian), Arwa (German), Orava (Estonian, Romanian, Slovak), Orawa (Polish) |
| Ostrobothnia | Bothnia Orientalis or Ostrobothnia (Latin), Botnie-Orientale (French), Österbotten (Swedish), Pohjanmaa (Estonian, Finnish) |
| Östergötland | Gothie orientale (French), Östergötland (Swedish), Östergötland (Estonian), Ostrogothia or Gothia Orientalis (Latin), Itä-Götanmaa (Finnish) |
| Overijssel | Oaveriesel (local Dutch Low Saxon dialects ), Oerisel (Frisian), Overijssel (Danish, Dutch, Estonian, French, German, Swedish) |
Read more about this topic: List Of European Regions With Alternative Names