| unter Wasser | underwater |
| Unterwasser- | undersea |
| Unterlassen | omission |
| unterlassen | stop |
| Unterklasse | subclass |
| Untertasse | saucer |
| Unterhalter | entertainer |
| Unterwäsche | underwear underclothes underclothing undergarments |
| unterdessen | in the meantime meanwhile |
| unterweisen | educate |
| Entermesser | cutlass |
| Alsterwasser | shandy |
| hartes Wasser | hard water |
| Feuerwasser | firewater |
| Meerwasser | seawater sea water |
| Unterdrücker | oppressor |
| Unterlagen | document |
| Unterstützer | contributor |
| Untersystem | sub-system |
| Unterwasserboot | submarine |