| Hydrogen | hydrogen |
| Hydrogenase | hydrogenase |
| Hydrogenium | hydrogen |
| Androgen | androgen |
| androgen | androgen |
| pyrogen | pyrogenic |
| Hydrologin | hydrologist |
| Hydroxyl | hydroxyl |
| hydrieren | hydrogenate |
| hydro- | hydro- |
| Hydrologe | hydrologist |
| Hydronym | hydronym |
| Hydroxid | hydroxide |
| Drogen- | narco- |
| Droge | drug |
| dröge | dry boring |
| Hadron | hadron |
| androgyn | androgynous |
| androhen | menace |
| bedrohen | threaten |