| Abbreviation | Definition |
|---|---|
| OSDFS | Office of Safe and Drug-Free Schools |
| OSEP | Office of Security and Emergency Preparedness |
| OSF | Office of Space Flight |
| OSH | Office of Supportive Housing |
| OSHRC | Occupational Safety and Health Review Commission |
| OSI | Office of Special Investigations |
| OSI | Office Of Strategic Intelligence |
| OSM | Office of Surface Mining |
| OSMRE | Office of Surface Mining Reclamation and Enforcement |
| OSMWRCC | Office of Surface Mining Western Regional Coordinating Center |
| OSP | Office of Special Programs |
| OSRA | Ocean Shipping Reform Act |
| OSRD | Office of Scientific Research and Development |
| OSTI | Office of Scientific and Technical Information |
| OT | Official Translation |
| OTC | Overseas Telecommunications Commission |
| OTF | Online Tax Filing |
| OTG | On The Go |
| OTH | Off The Hook |
| OTI | Office of Technology Integration |