| Reaktant | reactant |
| Reaktanz | reactance |
| Aktant | agent complement |
| Reaktion | reaction |
| Reaktor | reactor |
| Realität | reality |
| reaktiv | reactive |
| Traktat | treatise tract treaty |
| Oktant | Octans |
| rektal | rectal |
| Rattan | rattan |
| Sextant | sextant |
| Radiant | radian radiant |
| Rechtkant | cuboid |
| rasant | rapid |
| relevant | relevant |
| resonant | resonant |
| riskant | risky |
| vakant | vacant |
| Breakball | break point |