| Otwornice | Foraminifera |
| otyłość | obesidade |
| Otzing | Otzing |
| OUBZ | Organização do Tratado de Segurança Coletiva |
| Oudenaarde | Oudenaarde |
| Oudomxay | Subdivisões do Laos |
| Ouessant | Ouessant |
| Ouidah | Fortaleza de São João Baptista de Ajudá |
| Oulens-sous-Echallens | Oulens-sous-Echallens |
| Oulens-sur-Lucens | Oulens-sur-Lucens |
| OuLiPo | Oulipo |
| Oulu | Oulu |
| Our Love To Admire | Our Love To Admire |
| Ouran High School Host Club | Ouran High School Host Club |
| Ourense | Ourense |
| Ourique | Ourique |
| Ouro Preto | Ouro Preto |
| Out of Time | Out of Time |
| Outaouais | Outaouais |
| Outkast | OutKast |
| Outlawz | Outlawz |
| Outlook Express | Microsoft Outlook Express |
| Outpost Firewall Pro | Outpost Firewall Pro |
| Outubro | Outubro |
| Ouzo | Uzo |
| Ovalle | Ovalle |
| Over the Hills and Far Away | Over the Hills and Far Away |
| Overclocking | Overclocking |
| Overdubbing | Overdub |
| Overhalla | Overhalla |
| Overtakeovertook | Supreender |
| Overijssel | Overijssel |
| Oviedo | Oviedo |
| Ovis | Ovis |
| owad | bicho |
| Owadopylność | Entomofilia |
| owadoznawstwo | entomologia |
| Owadożerne | Insectívoros |
| Owady | Inseto |
| Owady bezskrzydłe | Apterygota |
| Owady uskrzydlone | Pterygota |
| Owal BA | Oval BA |
| owca | ovelha |
| Owca Dolly | Ovelha Dolly |
| Owca kanadyjska | Muflão |
| Owca w Wielkim Mieście | Sheep In The Big City |
| Owca śnieżna | Carneiro de Dall |
| owczarek | cão-pastor |
| Owczarek australijski | Pastor Australiano |
| owczarek belgijski | pastor belga |
| Owczarek belgijski Tervueren | Tervuren |
| owczarek chorwacki | pastor croata |
| Owczarek francuski Briard | Pastor de Brie |
| Owczarek kataloński | Pastor Catalão |
| owczarek niemiecki | pastor alemão |
| Owczarek portugalski | Cão da Serra de Aires |
| Owczarek staroangielski Bobtail | Old English Sheepdog |
| Owczarek szetlandzki | Pastor de Shetland |
| Owczarek szkocki długowłosy | Rough Collie |
| Owen | Owen |
| Owen Chamberlain | Owen Chamberlain |
| Owen Garriott | Owen Garriott |
| Owen Sound | Owen Sound |
| Owen Willans Richardson | Owen Willans Richardson |
| Owen Wilson | Owen Wilson |
| Owensboro | Owensboro |
| Owernia | Auvergne |
| Owidiusz | Ovídio |
| Owidiusz Decroly | Jean-Ovide Decroly |
| Owies | Aveia |
| owijać w bawełnę | enrolar |
| Owingen | Owingen |
| owinąć sobie kogoś wokół palca | encoleirar |
| Owiraptor | Oviráptor |
| Owiraptorozaury | Oviraptorosauria |
| OWL | OWL |
| owoc | fruta |
| Owocnik | Cogumelo |
| owocny | produtivo |
| owolaktarianizm | ovo-lakto vegetarianismo |
| Owsica | Enterobíase |
| Owsik ludzki | Cucurbitáceas |
| owszem | sim |
| Oxfam | Oxfam |
| Oxford | Oxford |
| Oxfordshire | Oxfordshire |
| Oxnard | Oxnard |
| Oxygène | Oxigénio |
| Oyem | Oyem |
| Oyo | Oió |
| Oz | Oz |
| Oz de Tena | Hoz de Jaca |
| Ozbeg | Uzbeg Khan |
| Ozdabiać klejnotami | Jewel |
| ozdobny | decorativo |
| Ozeasz | Oséias |
| oziębły | frio |
| oznaczanie | ensaios |
| Oznaczenia pochodzenia geograficznego productów rolnych w Unii Europejskiej | Denominação de Origem Protegida |
| Oznaczenia pochodzenia geograficznego produktów rolnych w Unii Europejskiej | Denominação de Origem Protegida |
| Oznaczyć coś gwiazdką | Asterisk |
| oznakowanie | rotulagem |
| Oznakowanie więźniów nazistowskich obozów | Os triângulos do Holocausto |
| ozon | ozono |
| Ozonosfera | Ozonosfera |
| ozonowanie | ozonização |
| Ozorka | Coeloglossum |
| Ozorka zielona | Coeloglossum |
| Ozyrys | Osíris |
