| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
| Odiste | city | Viljandimaa | Estonia | 58.4902778 | 25.9686111 | 170 | 1600 |
| Oissaare | city | Viljandimaa | Estonia | 58.25 | 25.05 | 190 | 1540 |
| Oisu | city | Viljandimaa | Estonia | 58.1972222 | 25.5502778 | 305 | 1615 |
| Oisu Asundus | city | Viljandimaa | Estonia | 58.1972222 | 25.5502778 | 305 | 1615 |
| Oiu | city | Viljandimaa | Estonia | 58.4177778 | 25.9661111 | 180 | 1396 |
| Ojakula | city | Viljandimaa | Estonia | 58.5497222 | 25.285 | 134 | 1588 |
| Ojaküla | city | Viljandimaa | Estonia | 58.5497222 | 25.285 | 134 | 1588 |
| Olustvere | city | Viljandimaa | Estonia | 58.5536111 | 25.5627778 | 262 | 1600 |
| Oniste | city | Viljandimaa | Estonia | 58.5072222 | 25.6475 | 275 | 1601 |
| Onniste | city | Viljandimaa | Estonia | 58.5072222 | 25.6475 | 275 | 1601 |
| Oorgu | city | Viljandimaa | Estonia | 58.5180556 | 25.8558333 | 209 | 1601 |
| Or'yatu | city | Viljandimaa | Estonia | 58.1991667 | 25.6891667 | 370 | 1615 |
| Orgu | city | Viljandimaa | Estonia | 58.5180556 | 25.8558333 | 209 | 1601 |
| Orjatu | city | Viljandimaa | Estonia | 58.1991667 | 25.6891667 | 370 | 1615 |
| Orʼyatu | city | Viljandimaa | Estonia | 58.1991667 | 25.6891667 | 370 | 1615 |
| Oti | city | Viljandimaa | Estonia | 58.1352778 | 25.5880556 | 295 | 1618 |
| Oti | city | Viljandimaa | Estonia | 58.4461111 | 25.9569444 | 154 | 1548 |
| Otikula | city | Viljandimaa | Estonia | 58.4461111 | 25.9569444 | 154 | 1548 |
| Otiküla | city | Viljandimaa | Estonia | 58.4461111 | 25.9569444 | 154 | 1548 |
| Oyakyula | city | Viljandimaa | Estonia | 58.5497222 | 25.285 | 134 | 1588 |
| Oyssare | city | Viljandimaa | Estonia | 58.25 | 25.05 | 190 | 1540 |
| Oyu | city | Viljandimaa | Estonia | 58.4177778 | 25.9661111 | 180 | 1396 |
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