| Latin name | Vernacular name (AACR2 form) | country code |
|---|---|---|
| Oeniponti* | Innsbruck (Austria) | au |
| Olisipone see Vlysipone | ||
| Olissipone see Vlysipone | ||
| Olom. see Olomucii | ||
| Olomucii* | Olomouc (Czech Republic) | xr |
| Olomuncii in Metropoli Morauiae see Olomucii | ||
| Olomutii see Olomucii | ||
| Olsnae* | Oels
(Germany) =Olesnica (Wroclaw, Poland) [both valid AACR2 headings] |
pl |
| Olsnae Silesiorum see Olsnae |
||
| Olysipone see Vlysipone | ||
| Olysippone see Vlysipone | ||
| Olyssipone see Vlysipone | ||
| Oppauiae* | Opava (Severomoravsky kraj, Czech Republic) | xr |
| Oppenheimii* | Oppenheim (Germany) | gw |
| Oppenheimio see Oppenheimii | ||
| Oppenhomii see Oppenheimii | ||
| Orcelis Bastitanorum see Oriolae | ||
| Oriolae* | Orihuela (Spain) | sp |
| Oriolani see Oriolae | ||
| Otthiniae* | Odense (Denmark) | dk |
| Oxon. see Oxoniis | ||
| Oxoniae see Oxoniis | ||
| Oxonias see Oxoniis | ||
| Oxonii see Oxoniis | ||
| Oxoniis* | Oxford (England) | enk |
| Oxonioe see Oxoniis | ||
| Oxonni see Oxoniis |