| Orthogon | rectangle |
| orthogonal | orthogonal |
| orthodox | orthodox |
| Oktogon | octagon |
| orthogonalität | orthogonality |
| Orthoepie | orthoepy |
| Orthofoto | orthophoto |
| Ortolan | ortolan |
| ortho- | ortho- |
| pathogen | pathogenic |
| Oktagon | octagon |
| Oregon | Oregon |
| Cortison | cortisone |
| Orthodoxie | Orthodoxy |
| Orthoklas | orthoclase |
| Vortragen | recitation |
| vortragen | recite execute perform ask for beg for solicit report lecture on talk about tell carry forward carry over |
| unorthodox | licentious |
| Kortholt | kortholt |
| Kortison | cortisone |