| Opéra Bastille | Opéra Bastille |
| Opéra comique | Opéra comique |
| Opéra Garnier | Palais Garnier |
| Opéra-Comique | Opéra-Comique |
| OR-poort | OR gate |
| oraal | spoken |
| Oraal rehydratiemiddel | Oral rehydration therapy |
| Oracle Corporation | Oracle Corporation |
| Oradea | Oradea |
| Oradour-sur-Glane | Oradour-sur-Glane |
| orakel | oracle |
| Orakel van Delphi | Delphic Sibyl |
| Orakel van Dodona | Dodona |
| orakelachtig | oracular |
| Oral | Ural |
| Oral Fixation Tour | Oral Fixation Tour |
| orale | gamahuche |
| Orale pathologie | Oral pathology |
| Orale seks | Oral sex |
| Oran | Oran |
| Orang oetan | Orangutan |
| Orang Pendek | Orang Pendek |
| orang-oetan | orangutan |
| orang-oetang | orangutan |
| Orang-oetans | Orangutan |
| Orange | Orange |
| Orange County Choppers | Orange County Choppers |
| Orange Walk | Orange Walk District |
| orangeade | orangeade |
| Oranienburg | Oranienburg |
| Oranienburger Straße | Oranienburger Straße |
| oranje | orange |
| Oranje Alternatief | Orange Alternative |
| Oranje havikskruid | Pilosella aurantiaca |
| Oranje luzernevlinder | Anxiety to |
| Oranje Orde | Orange Institution |
| Oranje passiebloemvlinder | Dryas julia |
| Oranje Revolutie | Orange Revolution |
| Oranje springzaad | Impatiens capensis |
| Oranje Vrijstaat | Orange Free State |
| Oranje wortelboorder | Orange Swift |
| Oranje zandoogje | Lily |
| Oranje-Nassau | House of Orange-Nassau |
| Oranje-Vrijstaat | Orange Free State |
| oranjeappel | orange |
| oranjeboom | orange-tree |
| Oranjegroene melkzwam | Lactarius deliciosus |
| oranjerie | orangery |
| Oranjerivier | Orange |
| Oranjerivier-Afrikaans | Afrikaans |
| Oranjerivierkolonie | Orange River Colony |
| oranjerood | carroty |
| Oranjetipje | Orange Tip |
| Oranjevrijstaat | Orange Free State |
| Orarion | Orarion |
| oratie | speech |
| Oratorianen | Oratory of Saint Philip Neri |
| oratorisch | oratorical |
| oratorium | oratorio |
| Orava | Orava Parish |
| Oravais | Oravais |
| Orb | Orb River |
| Orbassano | Orbassano |
| Orbe | Orbe |
| Orbetello | Orbetello |
| orbit | orbit |
| orbita | orbit |
