| Abbreviation | Definition |
|---|---|
| OCF | Open Clinical Foundation |
| OCFI | Obsessive Compulsive Foundation, Inc. |
| OCG | Orange County Guild |
| OCHA | Office for the Coordination of Humanitarian Affairs |
| OCI | Oil Change International |
| OCIC | Ontario Council for International Cooperation |
| OCMA | Ohio Coin Machine Association |
| OCMA | Orange County Medical Association |
| OCMC | Orthodox Christian Mission Center |
| OCMCI | Orthodox Christian Mission Center, Inc. |
| OCN | Open College Network |
| OCN | Oregon Conservation Network |
| OCNA | Ovarian Cancer National Alliance |
| OCNM | Oklahoma City National Memorial |
| OCNMT | Oklahoma City National Memorial Trust |
| OCO | Office of Children's Ombudsman |
| OCO | Office of Community Outreach |
| OCO | Orange Coast Optimist Club |
| OCO | Oswego County Opportunities, Inc. |
| OCPA | Orange County People for Animals |