| Abbreviation | Definition |
|---|---|
| OCRF | Ovarian Cancer Research Fund |
| OCRFSAC | Ovarian Cancer Research Fund Scientific Advisory Committee |
| OCSH | Ohio Coalition for Safe Highways |
| OCY | Old Colony YMCA |
| OCY | Ombudsman for Children and Youth |
| OD | Open Democracy |
| ODAA | Open Door Adoption Agency |
| ODBA | Open Doors with Brother Andrew |
| ODBAI | Open Doors with Brother Andrew, Inc. |
| ODCA | Oklahoma Dexter Cattle Association |
| ODCA | Old Downtown Carrollton Association |
| ODCF | Ogden Dunes Community Fund |
| ODCG | Organization for Development Care and Gender |
| ODCH | Open Door Community House |
| Odessa | Organisation Der Ehemaligen SS Angehoerigen |
| ODF | O`Donnell Foundation |
| ODG | Oregon Development Group |
| ODI | Open Discovery Initiative (of NISO) |
| ODI | Open Doors International |
| OEF | Osborn Educational Foundation |