| orphie | garfish |
| Orphisme | Orphism |
| Orphée | Orpheus |
| Orphée aux Enfers | Orpheus in the Underworld |
| Orpin âcre | Sedum acre |
| Orpund | Orpund |
| orque | orc |
| Orrin Hatch | Orrin Hatch |
| Orrorin tugenensis | Orrorin tugenensis |
| Orsanmichele | Orsanmichele |
| Orsay | Orsay |
| Orselina | Orselina |
| Orsha | Orsha |
| Orsières | Orsières |
| Orsk | Orsk |
| Orso Ier Participazio | Orso I Participazio |
| Orso II Participazio | Orso II Participazio |
| Orso Ipato | Orso Ipato |
| Orson Hodge | Orson Hodge |
| Orson Scott Card | Orson Scott Card |
| Orson Welles | Orson Welles |
| Orséis | Orseis |
| Ortac | Ortac |
| orteil | digit |
| Ortenau | Ortenaukreis |
| Orthanc | Orthanc |
| Orthetrum | Orthetrum |
| Orthetrum cancellatum | Black-tailed Skimmer |
| Orthez | Orthez |
| Ortho-nitrophenyl-β-galactoside | Ortho-Nitrophenyl-β-galactoside |
| Orthobicoupole pentagonale | Pentagonal orthobicupola |
| Orthobicoupole pentagonale allongée | Elongated pentagonal orthobicupola |
| Orthobicoupole triangulaire | Triangular orthobicupola |
| Orthobicoupole triangulaire allongée | Elongated triangular orthobicupola |
| Orthobirotonde pentagonale | Pentagonal orthobirotunda |
| Orthobirotonde pentagonale allongée | Elongated pentagonal orthobirotunda |
| Orthocoupole-rotonde pentagonale | Pentagonal orthocupolarotunda |
| Orthocoupole-rotonde pentagonale allongée | Elongated pentagonal orthocupolarotunda |
| orthodontie | orthodontics |
| orthodoxe | orthodox |
| Orthodoxes vieux-calendaristes | Greek Old Calendarists |
| Orthodoxes vieux-croyants | Old Believers |
| Orthodoxie de rite occidental | Western Rite Orthodoxy |
| Orthogastropoda | Orthogastropoda |
| Orthogonal Frequency Division Multiplexing | Orthogonal frequency-division multiplexing |
| Orthogonalement | Square |
| orthographe | spelling |
| orthographier | spell |
| orthographique | orthographic |
| orthogénie | family planning |
| Orthohydrogene | Orthohydrogen |
| Orthomyxoviridae | Orthomyxoviridae |
| Orthonychidae | Orthonychidae |
| Orthopantomogramme | Orthopantomogram |
| orthophonie | speech therapy |
| Orthophotographie | Orthophoto |
| Orthopnée | Orthopnoea |
| Orthoptera | Orthoptera |
| orthoptère | orthopteran |
| orthopédie | orthopedics |
| orthopédique | orthopedic |
| orthopédiste | orthopedist |
| Orthorexie | Orthorexia nervosa |
| Orthos | Orthrus |
| Orthosie | Orthosie |
| Orthostat | Megalithic architectural elements |
| Orthotypographie | Typographical syntax |
| Orthèse | Orthosis |
| ortie | stinging nettle |
