| Hohlwelttheorie | hollow-Earth theory |
| Zahlentheorie | theory of numbers |
| Wellentheorie | wave model wave theory |
| Spieltheorie | game theory |
| Zelltheorie | cell theory |
| Kohlechemie | carbochemistry |
| Wohlwünscherin | well-wisher |
| Knotentheorie | knot theory |
| Mengentheorie | set theory |
| Chaostheorie | chaos theory |
| Dramentheorie | dramatic theory |
| Graphentheorie | graph theory |
| Gruppentheorie | group theory |
| Pongidentheorie | Pongidae hypothesis |
| Quantentheorie | quantum theory |
| Systemtheorie | system theory |
| Urknalltheorie | Big Bang Theory |
| Koketterie | coquetry |
| Hoheitsrechte | regalia |
| Hohlbeitel | gouge |