| Abbreviation | Definition |
|---|---|
| OSIWA | Open Society Institute for West Africa |
| OSJ | Optical Society of Japan |
| OSK | \mYΠ|
| OSK | Optical Society of Korea |
| OSME | Ornithological Society of the Middle East |
| OSMS | Ogden Surgical Medical Society |
| OSMT | Ontario Society of Medical Technologists |
| OSNE | Orissa Society of New England |
| OSNZ | Ornithological Society of New Zealand |
| OSOS | Open Schools for Open Societies |
| OSP | Ontario Society of Psychotherapists |
| OSPA | Oregon Society of Physician Assistants |
| OSPC | Open Society Policy Center |
| OSPCA | Oahu Society for the Prevention of Cruelty to Animals |
| OSPE | Ohio Society of Professional Engineers |
| OSPE | Oklahoma Society of Professional Engineers |
| OSPE | Ontario Society of Professional Engineers |
| OSPS | Oklahoma Society for Psychoanalytic Studies |
| OSPS | Oklahoma Society for Pyschoanalytic Studies |
| OSQ | Oratorio Society of Queens |