| H/S/O | Hardware/Software/Operations 
| Others |
| HSO | Harrisburg Symphony Orchestra
| Others |
| HSO | Hartford Symphony Orchestra
| Others |
| HSO | Hawaii Symphony Orchestra
| Others |
| HSO | Head Sub Office
| Others |
| HSO | Health and Safety Officer
| Others |
| HSO | Health Sciences Online
| Others |
| HSO | Health Services Officer
| Others |
| HSO | Health Standards Organization
| Others |
| HSO | Heliophysics System Observatory
| Others |
| HSO | Help Sunil Out
| Others |
| HSO | Helping To Serve Others
| Others |
| HSO | Hemostatic Soil Organism
| Others |
| HSO | High School Outreach
| Others |
| HSO | High Speed Operation
| Others |
| HSO | High Speed Output
| Others |
| HSO | High Speed Oval
| Others |
| HSO | Highway Safety Office
| Others |
| HSO | Hindu Students Organization
| Others |
| HSO | Historic Simracing Organization
| Others |
| HSO | Hitless Switchover
| Others |
| HSO | Homeostatic Soil Organisms
| Others |
| HSO | Honors Student Organization
| Others |
| HSO | Honors Student Orientation
| Others |
| HSO | Honors Students Organization
| Others |
| HSO | Hopkins Symphony Orchestra
| Others |
| HSO | Housing Services Office
| Others |
| HSO | Houston Society of Otolaryngology
| Others |
| HSO | Human Subjects Office
| Others |
| HSO | Humboldt Seed Organization
| Others |
| HSO | Huntsville Symphony Orchestra
| Others |
| HSO | Thermal Enhanced Small Outline Package
| Others |