sort by Rank | Alpha
| Possible Meanings | Rank |
| Health Assessment and Promotion Examination | * |
| Hazardous Air Pollutant Enforcement | * |
| Hydrological Atmospheric Pilot Experiment | * |
| Hydrological Atmospheric Pilot Experiments | * |
| Hydrology Atmosphere Pilot Exper | * |
| Hydrology Atmosphere Pilot Experiment | * |