| Ortsordinarius | ordinary |
| Ordinarius | ordinary |
| Ordinariat | ordinariate |
| Stradivarius | Stradivarius |
| Koordination | coordination |
| Ordination | ordination |
| ordinär | ordinary common vulgar |
| Veterinärin | veterinarian |
| Autoritarismus | authoritarianism |
| Orthodoxie | Orthodoxy |
| Orthohelium | orthohelium |
| Orthoklas | orthoclase |
| Orthonitrat | orthonitrate |
| Orthorexie | orthorexia |
| Ortsermittlung | localization |
| Tortonium | Tortonian |
| orthogonalität | orthogonality |
| Opportunismus | opportunism |
| Orthognathie | orthognathy orthognathysm |
| Orthografie | orthography spelling |