| Abbreviation | Definition |
|---|---|
| OSRC | Ohio Society for Respiratory Care |
| OSRC | Oklahoma Society for Respiratory Care |
| OSRC | Oregon Society for Respiratory Care |
| OSSA | Ontario Society for the Study of Argumentation |
| OSSA | Ophthalmological Society of South Africa |
| OSSC | Optical Society of Southern California |
| OSSC | Orchid Society of Southern California |
| OSSEA | Ohio State Society of Enrolled Agents |
| OSSEA | Orchid Society of South East Asia |
| OSTA | Ohio Society of Traditional Archers |
| OSTC | Oregon Society of Tax Consultants |
| OSUM | Optics Society at the University of Michigan |
| OSWA | Organ Society of Western Australia |
| OTACS | Old Timer Assay Commission Society |
| OTDS | Odisha Tribal Development Society |
| OTHAS | One Tree Hill Allotment Society |
| OTLA | Ontario Trial Lawyers Association |
| OTS | Oligonucleotide Therapeutics Society |
| OTSA | Orthodox Theological Society in America |
| OUPS | Open University Psychological Society |