| orthoclase | Mondstein |
| orthodontia | Kieferorthopädie |
| orthodontic | kieferorthopädisch |
| orthodontic appliance | kieferorthopädischer Apparat |
| orthodontic braces | Zahnspange |
| orthodontic treatment | Zahnregulierung |
| orthodontics | Kieferorthopädie |
| orthodontist | Kieferorthopäde |
| orthodontists | Kieferorthopäden |
| orthodox | konventionell |
| Orthodox Christianity | Orthodoxe Kirchen |
| Orthodox Church in America | Orthodoxe Kirche in Amerika |
| Orthodox Church of Constantinople | Ökumenisches Patriarchat von Konstantinopel |
| Orthodox Judaism | Orthodoxes Judentum |
| orthodox medical | orthomedizinisch |
| orthodox medical practitioner | Schulmediziner |
| orthodox medicine | Schulmedizin |
| Orthodox Ohrid Archbishopric | Erzbistum Ohrid |
| Orthodox Patriarch of Jerusalem | Liste der Patriarchen von Jerusalem |
| orthodox theology | orthodoxe Theologie |
| orthodoxly | orthodox |
| orthodoxy | Lehrmeinung |
| Orthodrome | Großkreis |
| orthoepy | Orthoepie |
| orthoferrosilite | Ortho-Ferrosilit |
| Orthogastropoda | Orthogastropoda |
| orthogeosyncline | Orthogeosynklinale |
| orthognathic surgery | orthognathe Chirurgie |
| orthogneiss | Orthogneis |
| orthogonal | rechtwinklig |
| Orthogonal complement | Komplement |
| Orthogonal frequency-division multiplexing | OFDM |
| Orthogonal group | Orthogonale Gruppe |
| Orthogonal matrix | Orthogonale Matrix |
| orthogonal polarisation | orthogonale Polarisation |
| orthogonal polynomial | Orthogonalpolynom |
| orthogonal projection | rechtwinklige Projektion |
| orthogonal regression | orthogonale Regression |
| orthogonal system | Orthogonal-System |
| orthogonality | Rechtwinkligkeit |
| orthogonality constant | Orthogonalitätskonstante |
| orthogonally | orthogonal |
| orthographic | rechtwinklig |
| orthographic azimuthal projection | orthografische Azimutalprojektion |
| orthographic dictionary | Rechtschreibwörterbuch |
| orthographic projection | rechtwinklige Projektion |
