| Old Aker Church | Gamle Aker kirke |
| Old Bushmills Distillery | Bushmills |
| Old Catholic Church | Gammelkatolikker |
| Old Catholic Church of Austria | Gammelkatolikker |
| Old Catholic Mission in France | Gammelkatolikker |
| Old Church Slavonic | Oldkirkeslavisk |
| Old City | Staré Město |
| Old City of Jerusalem | Staré Město |
| Old conveyance | Båd |
| Old Danish Pointer | Gammel dansk hønsehund |
| Old Dominion | Virginia |
| Old Faithful Geyser | Old Faithful |
| Old Firm | The Old Firm |
| Old Friends from Young Years | Old Friends From Young Years |
| Old Gutnish | Gutnisk |
| old hazardous site | tidligere forurenet lokalitet |
| Old Hungarian script | Ungarske runer |
| old landfill site | gammel aflejring |
| Old Major | Gamle Major |
| Old Man and the Sea | Den gamle mand og havet |
| Old Men in New Cars | Gamle mænd i nye biler |
| Old Norse | Norrønt |
| Old Norse language | Norrønt |
| Old Nosy | Wellington |
| Old Persian | Gammelpersisk |
| Old Prussia | Preussen |
| Old Prussians | Preussen |
| Old school hip hop | Old school hip hop |
| Old Summer Palace | Det gamle kejserlige sommerpalads |
| Old Testament | Det Gamle Testamente |
| Old Town of Prague | Staré Město |
| Old Trafford | Old Trafford |
| Old World | Gamle Verden |
| Old World flycatcher | Grå fluesnapper |
| Old World monkey | Marekatte |
| Old World Swallowtail | Svalehale |
| Old World warbler | Sangere |
| Old-time music | Oldtime |
| Oldenburg | Oldenburg |
| older | ældre |
| oldest | ældst |
| Oldest people | Århundrede |
| Oldowan | Olduwan-kultur |
| Oldrich of Bohemia | Ulrik |
| Olduwan | Olduwan-kultur |
| Ole Bull | Ole Bull |
| Ole Gunnar Solskjær | Ole Gunnar Solskjær |
| Ole Madsen | Ole Eduard Fischer Madsen |
| Ole Nydahl | Ole Nydahl |
| Ole Rømer | Ole Rømer |
| Ole Worm | Ole Worm |
| Olea | Oliven-slægten |
| Oleaceae | Oliven-familien |
| Oleg Gordievsky | Oleg Gordievskij |
| Oleg Kotov | Oleg Kotov |
| Oleg Losev | Oleg Vladimirovich Losev |
| Oleksandriia | Alexandria |
| olfactory pollution | olfaktorisk forurening |
| Olga | Olga |
| Olga Korbut | Olga Korbut |
| Olga of Kiev | Olga |
| oligarchy | oligarki |
| Oligocene | Oligocæn |
| oligopoly | oligopol |
| Olimpia | Olympia |
| Olimpia Asunción | Olympia |
| olive | oliven |
| Olive Baboon | Anubisbavian |
| Olive oil | Olivenolie |
| olive oil mill wastewater | olierester |
| Olive-wood | Oliven |
| Oliveira | Oliven |
| Oliver | Oliven |
| Oliver Bierhoff | Oliver Bierhoff |
| Oliver Cromwell | Oliver Cromwell |
| Oliver Hardy | Oliver Hardy |
| Oliver Heaviside | Oliver Heaviside |
| Oliver Kahn | Oliver Kahn |
| Oliver Neuville | Oliver Neuville |
| Oliver Norvelle Hardy | Oliver Norvelle Hardy |
| Oliver Riedel | Oliver Riedel |
| Oliver St John Gogarty | Oliver St John Gogarty |
| Oliver Stone | Oliver Stone |
| Oliverio Rincón | Oliverio Rincón |
| Olives | Oliven |
| Olivia Newton-John | Olivia Newton-John |
| Olivier | Oliven |
| Olivier de Clisson | Olivier de Clisson |
| Olivier Messiaen | Olivier Messiaen |
| Olivine | Olivin |
| Ollie | Ollie |
| Olmec | Olmeker |
| Olmeca | Olmeker |
| Olof Palme | Olof Palme |
| Olof Palme assassination | Palmemordet |
| Olof Skötkonung | Olaf |
| Olofström Municipality | Olofströms kommun |
| Olomouc Synagogue | Synagoge |
| Olsen Brothers | Brødrene Olsen |
| Olsen Gang | Olsen-banden |
| Olsztyn | Olsztyn |
| OLT | Olt |
| Olt County | Olt |
| Oluf Haraldsen | Oluf Haraldsen |
| Olusegun Obasanjo | Olusegun Obasanjo |
| Olympia | Olympia |
| Olympiacos | Olympiakos |
| Olympiacos BC | Olympiakos |
| Olympiacos FC | Olympiakos |
| Olympiacos SC | Olympiakos |
| Olympiad | Olympiade |
| Olympiakos | Olympiakos |
| Olympias | Olympias |
| Olympic | Olympia |
| Olympic Flame | Olympiske ild |
| Olympic Games | Olympiske lege |
| Olympic Oath | Olympisk løfte |
| Olympic Peninsula | Olympique de Marseille |
| Olympic sport | Olympiske sportsgrene |
| Olympic sports | Olympiske sportsgrene |
| Olympic Stadium | Olympiastadion |
| Olympics | Olympiske lege |
| Olympique de Marseille | Olympique de Marseille |
| Olympique Lyonnais | Olympique Lyonnais |
| Olympisch Stadion | Olympisch Stadion |
| Olympos | Olympen |
| Olympus | Olympen |
| Olympus Mons | Olympus Mons |
| Olza River | Elleslægten |
| Olímpia | Olympia |
| Om mani padme hum | Mani |
| Om River | Aum |
| Omaha | Omaha |
| Omaha Beach | Omaha Beach |
| Oman | Oman |
| Omar al-Bashir | Omar al-Bashir |
| Omar Bradley | Omar Bradley |
| Omar Khayyám | Omar Khayyám |
| omega | omega |
| Omega particle | Omega |
| Omega SA | Omega |
| omelette | omelet |
| Omelette ¤ | Æggekage |
