| Ordino | Ordino |
| Ordizia | Ordizia |
| ordnance | artillerie |
| Ordo Templi Orientis | Ordo Templi Orientis |
| Ordovician | Ordovicium |
| Ordoño I of Asturias | Ordoño I van Asturië |
| Ordoño II of León | Ordoño II van León |
| Ordoño III of León | Ordoño III van León |
| Ordre de la Libération | Orde van de Bevrijding |
| Ordre des Arts et des Lettres | Orde van Kunst en Letteren |
| Ordre des Palmes Académiques | Orde van de Academische Palmen |
| Ordre national du Mérite | Nationale Orde van Verdienste |
| Ordu | Ordu |
| Ordu Province | Ordu |
| ordure | vuil |
| Orduspor | Orduspor |
| Orduña | Urduña |
| Ordzhonikidze | Vladikavkaz |
| ore | erts |
| Ore Mountains | Ertsgebergte |
| Oreads | Oreaden |
| Orebić | Pelješac |
| oregano | oregano |
| Oregon | Oregon |
| Oregon - Salem | Staten van de Verenigde Staten |
| Oregon City | Oregon City |
| Oregon Country | Oregon Country |
| Oregon Territory | Oregonterritorium |
| Oregon Trail | Oregon Trail |
| Oregon-grape | Mahonia |
| Orel | Orel |
| Orellana Province | Orellana |
| Orem | Orem |
| Orenburg | Orenburg |
| Orenburg Airlines | Orenburg Airlines |
| Orenburg Oblast | Oblast Orenburg |
| Orendain | Orendain |
| Orense | Ourense |
| Oreochromis mossambicus | Natalbaars |
| Orestes | Orestes |
| Orestiada | Orestie |
| Oresund | Sont |
| Oresund Bridge | Sontbrug |
| Oresund Region | Öresundregio |
| Orexa | Orexa |
| Oreye | Oerle |
| Orfeas | Orpheus |
| Orfeo ed Euridice | Orpheus |
| Orff Schulwerk | Orff-Schulwerk |
| Orfgen | Orfgen |
| organ | harmonium |
| organ-grinder | orgeldraaier |
| Organelle | Organel |
| organic | organisch |
| Organic architecture | Organische architectuur |
| Organic chemistry | Organische chemie |
| Organic compound | Organische verbinding |
| organic food | natuurvoeding |
| Organic light-emitting diode | Organische Licht Emitterende Diode |
| Organic nomenclature | IUPAC-nomenclatuur |
| Organic reaction | Organische synthese |
