| Hydroxid | hydroxide |
| Hydroxidion | hydroxide |
| Hydroxyl | hydroxyl |
| Hydrid | hydride |
| Hydrogen | hydrogen |
| hydro- | hydro- |
| Hydronym | hydronym |
| hydrophil | hydrophilic |
| Android | android |
| Boroxid | boron oxide |
| Peroxid | peroxide |
| Dioxid | dioxide |
| Hypoxie | hypoxia hypoxaemia oxygen deficiency oxygen depletion |
| Hydra | Hydra Lernaean Hydra |
| Hydrat | hydrate |
| Hydrologin | hydrologist |
| Hydrant | hydrant fire hydrant fireplug |
| Hydraulik | hydraulics hydraulic system |
| Hydrologe | hydrologist |
| Hydrologie | hydrology |