| Hydroxyl | hydroxyl |
| Hydronym | hydronym |
| Hydroxid | hydroxide |
| Hydrogen | hydrogen |
| hydro- | hydro- |
| Hydrolyse | hydrolysis |
| hydrophil | hydrophilic |
| Hydra | Hydra Lernaean Hydra |
| Hydrat | hydrate |
| Hydrant | hydrant fire hydrant fireplug |
| Hydrid | hydride |
| Hydrologe | hydrologist |
| Hydronymie | hydronymy |
| hydrophob | hydrophobic |
| Hadron | hadron |
| androgyn | androgynous |
| Proxy | proxy |
| Pyroxen | pyroxene |
| Enhydros | enhydros |
| Hydrokultur | hydroponics |