| otchłań | abyss |
| Otello | Othello |
| Otep | OTEP |
| Otepää | Otepää |
| Otfried von Weißenburg | Otfrid of Weissenburg |
| Othenio Abel | Othenio Abel |
| Other Voices | Other Voices |
| Otherkin | Otherkin |
| Othniel Charles Marsh | Othniel Charles Marsh |
| Oti | Oti River |
| Otis Redding | Otis Redding |
| Otmar Hasler | Otmar Hasler |
| otmuchowianin | resident of Otmuchów |
| Otmuchów | Otmuchów |
| Otniel | Othniel Ben Kenaz |
| Otnielia | Othnielia |
| Otnielozaur | Othnielosaurus |
| Otocinclus | Otocinclus |
| Otocinclus affinis | Otocinclus affinis |
| otocjon | bat-eared fox |
| otoczak | cobblestone |
| otoczenie | ambience |
| Otoczenie Ramzesa II | List of children of Ramesses II |
| otoczyć | encompass |
| Otoemisja akustyczna | Otoacoustic emission |
| Otranto | Strait of Otranto |
| OTRS | OTRS |
| otrzymywać | receive |
| otręby | bran |
| Ottavio Bottecchia | Ottavio Bottecchia |
| Ottawa | Ottawa |
| Ottawa Senators | Ottawa Senators |
| Ottawowie | Ottawa |
| Ottenhofen | Ottenhofen |
| Ottenhöfen im Schwarzwald | Ottenhöfen |
| Ottensoos | Ottensoos |
| Otterfing | Otterfing |
| Ottersweier | Ottersweier |
| Otting | Otting |
| Otto | Otto |
| Otto Addo | Otto Addo |
| Otto Barić | Otto Barić |
| Otto Bauer | Otto Bauer |
| Otto Blehr | Otto Blehr |
| Otto Diels | Otto Diels |
| Otto Dix | Otto Dix |
| Otto Franciszek Austriacki | Archduke Otto Franz of Austria |
| Otto Globocnik | Odilo Globocnik |
| Otto Hahn | Otto Hahn |
| Otto Heinrich Warburg | Otto Heinrich Warburg |
| Otto I Piękny | Otto of Greece |
| Otto II z Montferratu | Otto II of Montferrat |
| Otto Jespersen | Otto Jespersen |
| Otto Klemperer | Otto Klemperer |
| Otto Kotzebue | Otto von Kotzebue |
| Otto Kuusinen | Otto Ville Kuusinen |
| Otto Lilienthal | Otto Lilienthal |
| Otto Meyerhof | Otto Fritz Meyerhof |
| Otto Mueller | Otto Mueller |
| Otto Nerz | Otto Nerz |
| Otto Preminger | Otto Preminger |
| Otto Pérez Molina | Otto Pérez Molina |
| Otto Rank | Otto Rank |
| Otto Rehhagel | Otto Rehhagel |
| Otto Skorzeny | Otto Skorzeny |
| Otto Stern | Otto Stern |
| Otto Strandman | Otto Strandman |
| Otto Szmidt | Otto Schmidt |
| Otto Thierack | Otto Georg Thierack |
| Otto von Bismarck | Otto von Bismarck |
| Otto von Guericke | Otto von Guericke |
| Otto von Habsburg | Otto von Habsburg |
| Otto von Wächter | Otto Wächter |
| Otto Wagner | Otto Wagner |
| Otto Wallach | Otto Wallach |
| Otto Weininger | Otto Weininger |
| Otto Witte | Otto Witte |
| Otto Wittelsbach | Otto of Greece |
| Otto z Bambergu | Otto of Bamberg |
| Ottobeuren | Ottobeuren |
| Ottobrunn | Ottobrunn |
| Otton I | Otto I |
| Otton I Wielki | Otto I |
| Otton I Wittelsbach | Otto of Greece |
| Otton Orseolo | Otto Orseolo |
| Ottone Visconti | Ottone Visconti |
| Ottorino Respighi | Ottorino Respighi |
| Ottrau | Ottrau |
| Ottón Solís | Ottón Solís |
| otucha | comfort |
| otwarcie | open |
| Otwarcie Barnesa | Barnes Opening |
| Otwarcie szachowe | Chess opening |
| Otwarta ramka odczytu | Open reading frame |
| otwarte morze | open sea |
| Otwarte oprogramowanie | Open source |
| Otwartopęcherzowe | Ostariophysi |
| otwarty | open |
| Otwarty standard | Open standard |
| Otwarty Uniwersytet Izraela | Open University of Israel |
| otwieracz | opener |
| otwieracz do butelek | bottle opener |
| otwieracz do konserw | can opener |
| otwieracz do puszek | can opener |
| Otwieraă | Open out |
| otwierać | open |
| Otwock | Otwock |
| Otwornice | Foraminifera |
| otwór | vent |
| Otwórz oczy | Abre los ojos |
| otyłość | obesity |
| Otyłość brzuszna | Central obesity |
| otyły | puffy |
| Otzberg | Otzberg |
| Otzing | Otzing |
| Ouaddaï | Ouaddai Empire |
| OUBZ | Collective Security Treaty Organisation |
| Oudenaarde | Oudenaarde |
| Oudomxay | Oudomxai Province |
| Ouessant | Ushant |
| Oulainen | Oulainen |
| 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 |
| Ouro-Nimini Tchagnirou | Ouro-Nimini Tchagnirou |
| Ousmane Issoufi Maïga | Ousmane Issoufi Maïga |
| Out From Out Where | Out from Out Where |
| Outaouais | Ottawa River |
| Outkast | OutKast |
| Outlawz | Outlawz |
| Outlook Express | Outlook Express |
| Outpost Firewall Pro | Outpost Firewall Pro |
| Outubro | Outubro |
| Ovadia Yosef | Ovadia Yosef |
| Ovar | Ovar |
| Ove Høegh-Guldberg | Ove Høegh-Guldberg |
| Ove Sprogøe | Ove Sprogøe |
| Over the Hills and Far Away | Over the Hills and Far Away |
| Overclocking | Overclocking |
| Overhalla | Overhalla |
| Overijssel | Overijssel |
| Oviedo | Oviedo |
| Ovis | Ovis |
| OVRA | OVRA |
| OVS | Object Verb Subject |
| owacja | ovation |
| owad | insect |
| owadoznawstwo | entomology |
| Owadożerne | Insectivora |
| Owady | Insect |
| Owady bezskrzydłe | Apterygota |
| Owady uskrzydlone | Pterygota |
| owal | oval |
| Owal BA | Oval BA |
| Owal Cassiniego | Cassini oval |
| owalen | ovalene |
| owca | ewe |
| Owca Dolly | Dolly |
| Owca domowa | Mutton |
| Owca kanadyjska | Mouflon sheep |
| Owca w Wielkim Mieście | Sheep in the Big City |
| Owca śnieżna | Dall Sheep |
| owczarek | sheepdog |
| Owczarek australijski | Australian Shepherd |
| owczarek belgijski | Belgian Sheepdog |
| Owczarek belgijski Groenendael | Belgian Shepherd Dog |
| Owczarek belgijski Laekenois | Belgian Shepherd Dog |
| Owczarek belgijski Malinois | Belgian Shepherd Dog |
| Owczarek belgijski Tervueren | Belgian Shepherd Dog |
| owczarek chorwacki | Croatian Sheepdog |
| Owczarek francuski Beauceron | Beauceron |
| Owczarek francuski Briard | Briard |
| Owczarek holenderski | Dutch Shepherd Dog |
| Owczarek kataloński | Catalan Sheepdog |
| Owczarek kaukaski | Caucasian Shepherd Dog |
| owczarek niemiecki | German Shepherd |
| Owczarek pikardyjski | Berger Picard |
| Owczarek pirenejski | Pyrenean Shepherd |
| Owczarek południoworosyjski Jużak | South Russian Ovcharka |
| Owczarek staroangielski Bobtail | Old English Sheepdog |
| Owczarek szetlandzki | Shetlander |
| Owczarek szkocki krótkowłosy | Smooth Collie |
| Owczarek środkowoazjatycki | Central Asian Shepherd Dog |
| owczy | sheep |
| Owen Arthur | Owen Arthur |
| Owen Beck | Owen Beck |
| Owen Chamberlain | Owen Chamberlain |
| Owen Glendower | Owain Glyndŵr |
| Owen Guinn Smith | Guinn Smith |
| Owen Sound Attack | Owen Sound Attack |
| Owen Willans Richardson | Owen Willans Richardson |
| Owen Wilson | Owen Wilson |
| Owerlok | Overlock |
| Owernia | Auvergne |
| Owerniacki | Auvergnat |
| Owerniak | Auvergnat |
| Owidiusz | Ovid |
| Owidiusz Decroly | Ovide Decroly |
| owieczka | yeanling |
| owies | oats |
| owijać w bawełnę | beat around the bush |
| Owingen | Owingen |
| owinąć sobie kogoś wokół palca | wrap around one's little finger |
| Owiraptor | Oviraptor |
| Owiraptorozaury | Oviraptorosauria |
| OWL | Web Ontology Language |
| owoc | fruit |
| Owocnik | Fungi |
