| Ohio | Ohio |
| Ohio Wesleyan University | Wesleyan-universitetet |
| ohm | ohm |
| Ohmmètre | Ohmmeter |
| Ohrid | Ohrid |
| oie | gås |
| oie cendrée | grågås |
| oignon | løg |
| Oignon rouge | Løg |
| Oise | Oise |
| oiseau | fugl |
| oiseau chanteur | sanglærke |
| Oiseau de feu | Firebird |
| oiseau de paradis | paradisfugl |
| oiseau de proie | rovfugle |
| oiseau migrateur | trækfugle |
| Oiseau-tonnerre | Thunderbird |
| Oiseaux | Fugl |
| Oiseaux de basse-cour | Fjerkræ |
| oiseaux nicheurs | ynglefugle |
| oiselet | fugl |
| oiselle | fugl |
| oisillon | fugleunge |
| OK | Okay |
| Okapi | Okapi |
| Okhrid | Ohrid |
| Okinawa | Okinawa |
| Okinawa Honto | Okinawa |
| Okinawa Island | Okinawa |
| Oklahoma | Oklahoma |
| Oklahoma City | Oklahoma City |
| Oksana Akinchina | Oksana Akinsjina |
| Oktoberfest | Oktoberfest |
| OL | Ol |
| Ola | Vægten |
| Olaf Ier de Norvège | Olav Tryggvason |
| Olaf II de Norvège | Olav den Hellige |
| Olaf III de Norvège | Olav Kyrre |
| Olaf IV de Norvège | Olav Magnusson |
| Olanzapine | Zyprexa |
| Olaus Magnus | Olaus Magnus |
| Old Faithful | Old Faithful |
| Old Firm | The Old Firm |
| Old Friends From Young Years | Old Friends From Young Years |
| Old school | Old school |
| Old Trafford | Old Trafford |
| Old-time music | Oldtime |
| Oldenbourg | Oldenburg |
| Oldenburg | Oldenburg |
| Oldowayen | Olduwan-kultur |
| Ole Bull | Ole Bull |
| Ole Christensen Rømer | Ole Rømer |
| Ole Gunnar Solskjær | Ole Gunnar Solskjær |
| Ole Madsen | Ole Eduard Fischer Madsen |
| Ole Worm | Ole Worm |
| Olea | Oliven-slægten |
| Oleaceae | Oliven-familien |
| Oleg Gordievsky | Oleg Gordievskij |
| Oleg Kotov | Oleg Kotov |
| Oleg Vladimirovich Losev | Oleg Vladimirovich Losev |
| Olenegorsk | Olenegorsk |
| Olenogorsk | Olenegorsk |
| Olga | Olga |
| Olga Alexandrovna | Storhertuginde Olga Alexandrovna af Rusland |
| Olga Alexandrovna de Russie | Storhertuginde Olga Alexandrovna af Rusland |
| Olga Korbut | Olga Korbut |
| Olga Prekrasa | Olga |
| Olgoï-Khorkhoï | Mongolsk dødsorm |
| oligarchie | oligarki |
| Oligocène | Oligocæn |
| oligopole | oligopol |
| olisbos | dildo |
| olive | oliven |
| Oliveira | Oliven |
| Oliver Bierhoff | Oliver Bierhoff |
| Oliver Cromwell | Oliver Cromwell |
| Oliver Heaviside | Oliver Heaviside |
| Oliver Kahn | Oliver Kahn |
| Oliver Neuville | Oliver Neuville |
| Oliver Riedel | Oliver Riedel |
| Oliver St John Gogarty | Oliver St John Gogarty |
| Oliver Stone | Oliver Stone |
| Olivia Newton-John | Olivia Newton-John |
| Olivier | Oliven |
| Olivier européen | Oliven |
| Olivier IV de Clisson | Olivier de Clisson |
| Olivier Messiaen | Olivier Messiaen |
| Olivier V de Clisson | Olivier de Clisson |
| Olivine | Olivin |
| Ollie | Ollie |
| Olmèques | Olmeker |
| Olof de Suède | Olaf |
| Olof Palme | Olof Palme |
| Olsen Brothers | Brødrene Olsen |
| Olsztyn | Olsztyn |
| Oluf Ier de Danemark | Oluf Hunger |
| Oluf II de Danemark | Oluf II Haraldsen |
| Olusegun Obasanjo | Olusegun Obasanjo |
| Olympe | Olympen |
| Olympia | Olympia |
| Olympiades internationales de mathématiques | Internationale Matematik-Olympiade |
| Olympiakos | Olympiakos |
| Olympiakos Le Pirée | Olympiakos |
| Olympiakós | Olympiakos |
| Olympias | Olympias |
| Olympie | Olympia |
| Olympion | Templet for den Olympiske Zeus |
| Olympique de Marseille | Olympique de Marseille |
| Olympique lyonnais | Olympique Lyonnais |
| Olympiéion | Templet for den Olympiske Zeus |
| Olympos | Olympen |
| Olympus Mons | Olympus Mons |
| oléoduc | olierørledning |
| OM | Ohm |
| Omaha | Omaha |
| Omaha Beach | Omaha Beach |
| Oman | Oman |
