| Osiek | Osiek |
| Osiel Cárdenas | Osiel Cárdenas |
| Osijek | Osijek |
| Osijek-Baranja | Osijek-Baranja County |
| Osilnica | Osilnica |
| Osip Mandelstam | Osip Mandelstam |
| Osiris | Osiris |
| Osiris Shoes | Osiris |
| Osismii | Osismii |
| Oskar Kokoschka | Oskar Kokoschka |
| Oskar Lafontaine | Oskar Lafontaine |
| Oskar Maria Graf | Oskar Maria Graf |
| Oskar Morgenstern | Oskar Morgenstern |
| Oskar Neumann | Oscar Rudolph Neumann |
| Oskar Pastior | Oskar Pastior |
| Oskar Schindler | Oskar Schindler |
| Oskar Ursinus | Oskar Ursinus |
| Oskar-Helene-Heim | Oskar-Helene-Heim |
| Oskari Tokoi | Oskari Tokoi |
| Oskarshamn | Oskarshamn Municipality |
| Oskisch | Oscan language |
| Oslip | Oslip |
| Oslo | Oslo |
| Oslo-akkoorden | Oslo Accords |
| Osloer Straße | Osloer Straße |
| Oslofjord | Oslofjord |
| Osloß | Osloß |
| Osmaans | Ottoman |
| Osmaanse Rijk | Ottoman Empire |
| Osman | Osman |
| Osman I | Osman I |
| Osman II | Osman II |
| Osman III | Osman III |
| Osmaniye | Osmaniye Province |
| Osmar Daniel Ferreyra | Osmar Ferreyra |
| osmium | osmium |
| Osmolariteit | Osmole |
| osmose | osmosis |
| osmotisch | osmotic |
| Osmussaar | Osmussaar |
| Osnabrück | Osnabrück |
| Osnago | Osnago |
| Osoega | Osuga River |
| Osogbo | Osogbo |
| Osogna | Osogna |
| Osorkon de Oudere | Osorkon the Elder |
| Osorkon I | Osorkon I |
| Osorkon II | Osorkon II |
| Osorkon III | Osorkon III |
| Osorkon IV | Osorkon IV |
| OSPAR-Verdrag | Convention for the Protection of the Marine Environment of the North-East Atlantic |
| Osric | Osric of Deira |
| Osroene | Osroene |
| Osroes II | Osroes II of Parthia |
| Ossa | Ossa |
| Osseet | Ossetian |
| Ossekikker | Banded bull frog |
| Ossenbloed | Caput mortuum |
| Ossenhaas | Net |
| Ossenhoeder | Boötes |
| Osseointegratie | Osseointegration |
| Ossessione | Ossessione |
| ossestaart | oxtail |
| Ossetisch | Ossetic language |
| Ossetië | Ossetia |
| Ossewa Brandwag | Ossewabrandwag |
| Ossiach | Ossiach |
| Ossiacher See | Lake Ossiach |
| ossificatie | ossification |
| Ossingen | Ossingen |
| Ossip Bernstein | Ossip Bernstein |
| Ossip Zadkine | Ossip Zadkine |
| Osso buco | Ossobuco |
| Ossuaire van Douaumont | Douaumont ossuary |
| Ossuarium | Skeleton Transformer |
| Ossuccio | Ossuccio |
| Ost Autobahn | Ostautobahn |
| Ostalbkreis | Ostalbkreis |
| Ostalgie | Ostalgie |
| Ostallgäu | Ostallgäu |
| Ostankino-toren | Ostankino Tower |
| Ostare | Eostre |
| Ostasjkov | Ostashkov |
| Ostbevern | Ostbevern |
| Osteel | Osteel |
| Osteichthyes | Osteichthyes |
| Ostelsheim | Ostelsheim |
| Osten | Osten |
| ostentatief | ostentatiously |
| Osteocephalus | Slender-legged Treefrogs |
| Osteofyt | Bone spur |
