| reaktiv | reactive |
| reaktivieren | rehabilitate |
| Reaktion | reaction |
| Reaktor | reactor |
| kreativ | creative |
| inaktiv | dormant |
| Aktiv | active voice |
| aktiv | active |
| proaktiv | proactive |
| relativ | relative |
| Reaktant | reactant |
| Realteil | real part |
| freakig | freakish |
| Reaktanz | reactance |
| Aktiva | asset |
| überaktiv | hyperactive |
| Aktie | share stock |
| Aktin | actin |
| Praktik | practice |
| Redaktion | editing |