| otras | other |
| otro | other |
| otro lado | other side |
| otro mundo | afterlife |
| otro más | another |
| otro sitio | somewhere else |
| otro yo | alter ego |
| otrora | formerly |
| otros | other |
| Otros Mundos | Elseworlds |
| OTSC | Collective Security Treaty Organisation |
| Ottavio Bottecchia | Ottavio Bottecchia |
| Ottawa | Ottawa |
| Ottawa Senators | Ottawa Senators |
| Otterfing | Otterfing |
| Otto Bauer | Otto Bauer |
| Otto Beisheim | Otto Beisheim |
| Otto Blathy | Ottó Bláthy |
| Otto Braun | Otto Braun |
| Otto de Freising | Otto of Freising |
| Otto de Habsburgo | Otto von Habsburg |
| Otto Dietrich | Otto Dietrich |
| Otto Dix | Otto Dix |
| Otto Finsch | Otto Finsch |
| Otto Fritz Meyerhof | Otto Fritz Meyerhof |
| Otto Hahn | Otto Hahn |
| Otto Heinrich Frank | Otto Frank |
| Otto Heinrich Warburg | Otto Heinrich Warburg |
| Otto Hölder | Otto Hölder |
| Otto I de Saboya | Otto of Savoy |
| Otto Jespersen | Otto Jespersen |
| Otto Klemperer | Otto Klemperer |
| Otto Kuusinen | Otto Ville Kuusinen |
| Otto Lilienthal | Otto Lilienthal |
| Otto Lohmüller | Otto Lohmüller |
| Otto Mann | Otto Mann |
| Otto Mueller | Otto Mueller |
| Otto Nordenskjöld | Otto Nordenskiöld |
| Otto Paul Hermann Diels | Otto Diels |
| Otto Preminger | Otto Preminger |
| Otto Pérez Molina | Otto Pérez Molina |
| Otto Rahn | Otto Rahn |
| Otto Rank | Otto Rank |
| Otto Robert Frisch | Otto Robert Frisch |
| Otto Sander | Otto Sander |
| Otto Schaden | Otto Schaden |
| Otto Skorzeny | Otto Skorzeny |
| Otto Stern | Otto Stern |
| Otto von Bismarck | Otto von Bismarck |
| Otto von Guericke | Otto von Guericke |
| Otto von Kotzebue | Otto von Kotzebue |
| Otto von Spreckelsen | Johann Otto von Spreckelsen |
| Otto Wagner | Otto Wagner |
| Otto Wallach | Otto Wallach |
| Otto Wichterle | Otto Wichterle |
| Ottokar Novacek | Ottokar Novacek |
| Ottorino Respighi | Ottorino Respighi |
| Ottón Solís Fallas | Ottón Solís |
| Otus scops | European Scops Owl |
| Otón | Otho |
| Otón de Freising | Otto of Freising |
| Otón I de Alemania | Otto I |
| Otón I de Grecia | Otto of Greece |
| Otón I de Montferrato | Otto I of Montferrat |
| Otón II de Montferrato | Otto II of Montferrat |
| Otón IV de Brunswick-Grubenhagen | Otto |
| Otón Visconti | Ottone Visconti |
| Ouadane | Ouadane |
| Ouadi Qadisha | Kadisha Valley |
| Oualata | Oualata |
| Oudenaarde | Oudenaarde |
| Ouessant | Ushant |
| ouh | d'oh |
| OUI | Organizationally Unique Identifier |
| Oujda | Oujda |
| Oulens-sous-Echallens | Oulens-sous-Echallens |
| Oulens-sur-Lucens | Oulens-sur-Lucens |
| Oulipo | Oulipo |
| Oulu | Oulu |
| Our Lips Are Sealed | Our Lips Are Sealed |
| Our Worlds At War | Our Worlds at War |
| Ouran High School Host Club | Ouran High School Host Club |
| Ouranosaurus | Ouranosaurus |
| Ourea | Ourea |
| Ourique | Ourique |
| Ouro Preto | Ouro Preto |
| Ourunapithecus | Ouranopithecus macedoniensis |
| Ouse | River Great Ouse |
| Ousmane Issoufi Maïga | Ousmane Issoufi Maïga |
| Ousmane Sembène | Ousmane Sembène |
| Out of Africa | Out of Africa |
| Out Stack | Out Stack |
| Outaouais | Ottawa River |
| Outgames mundiales | World Outgames |
| Outkast | OutKast |
| Outlawz | Outlawz |
| Outlook Express | Outlook Express |
| Outremer | Outremer |
| Ouyang Xiu | Ouyang Xiu |
| Ouémé | Ouémé Department |
| ovación | applause |
| Ovadia Yosef | Ovadia Yosef |
| oval | egg-shaped |
| ovalado | oval |
| Ovambo | Ovambo |
| Ovamboland | Ovamboland |
| ovario | ovary |
| oveja | ewe |
| Oveja Dolly | Dolly |
| oveja madre | ewe |
| oveja negra | black sheep |
| ovejero | shepherd |
| Overclock | Overclocking |
| Overol | Dungarees |
| Overijssel | Overijssel |
| Ovezgeldy Atayev | Öwezgeldi Ataýew |
| Ovidio | Ovid |
