| Abbreviation | Definition |
|---|---|
| Ho | Holmium |
| HOCO | Highest Occupied Crystal Orbital |
| HOG | High Osmolarity Glycerol |
| HOG | high-osmolarity glycerol |
| HOH | Hydrogen Hydroxide |
| HOMO(s) | highest occupied molecular orbital(s) |
| HOMS | Hands On Molecular Science |
| HONO | Nitrous Acid |
| HONO | nitrous oxide |
| HOPES | Helping Orphans Physically Emotionally And Spiritually |
| HOQS | Highest Occupied Quantum State |
| HOSA | Hydroxylamine O Sulfonic Acid |
| HPAE | High Ph Anion Exchange |
| HPHe | High Pressure Helium |
| HPHT | High Pressure, High Temperature |
| HPLA | Hydroxy Phenyl Lactic Acid |
| HPMC | HydroxyPropyl MethylCellulose |
| HPSV | High Pressure Sodium Vapor |
| HPTSO | Heptamethyltrisiloxane |
| HRA | Happy Room Academy |