| Systemtheorie | system theory |
| Knotentheorie | knot theory |
| Spieltheorie | game theory |
| systemoid | systemoid |
| Mengentheorie | set theory |
| Dramentheorie | dramatic theory |
| Musiktheorie | music theory |
| Quantentheorie | quantum theory |
| Sprachtheorie | linguistic theory theory of language |
| Staatstheorie | theory of the state |
| Stringtheorie | string theory |
| Wellentheorie | wave model wave theory |
| Zahlentheorie | theory of numbers |
| Dysenterie | dysentery |
| Systemanalyse | systems analysis |
| Systematik | systematics |
| systemlos | systemless unmethodical without a system |
| Hysterikerin | hysteric |
| Hysterektomie | hysterectomy |
| Hysterie | hysteria hysterics |