| Abbreviation | Definition |
|---|---|
| OSDE | Oklahoma State Department of Education |
| OSDH | Oklahoma State Department of Health |
| OSGP | Oregon Savings Growth Plan |
| OSHA | Occupational Safety and Health Administration |
| OSHPD | Office of Statewide Health Planning and Development |
| OSHPTG | Ontario Senior Homeowners' Property Tax Grant |
| OSPL | open space and park land |
| OSR | Office of State Revenue |
| OSRTC | Ontario Sound Recording Tax Credit |
| OSS | Ontario Shared Services |
| OSS | Ottawa, Sandusky, Seneca County, Ohio |
| OSSG | Osun State Government |
| OSSPAC | Oregon Seismic Safety Policy Advisory Commission |
| OSTC | Ontario Sales Tax Credit |
| OSV | OceanSide Village |
| OSV | Old Sturbridge Village |
| OSW | Office of Solid Waste |
| OT | Oklahoma Territory |
| OT | Old Town |
| OT | Oregon Territory |