| Hydroxygruppe | hydroxy hydroxyl group |
| Carboxygruppe | carboxyl group |
| Hydrographie | hydrography |
| Hydrotherapie | hydrotherapy |
| Chromgruppe | chromium group |
| Haplogruppe | haplogroup |
| Rockgruppe | rock group |
| Euro-Gruppe | Eurogroup |
| Terrorgruppe | terror group |
| Hydroenergie | hydropower |
| Hydrogenase | hydrogenase |
| Hydroxyl | hydroxyl |
| Hydrochorie | hydrochory |
| Hydrologe | hydrologist |
| Hydrologie | hydrology |
| Hydrolyse | hydrolysis |
| Hydronymie | hydronymy |
| Adverbgruppe | adverbial phrase |
| Dreiergruppe | trio |
| Kontrollgruppe | control |