| Abbreviation | Definition |
|---|---|
| OHCC | Oak Hills Christian College |
| OHSC | Oxford Home Study College |
| OICU | Oklahoma Independent Colleges and Universities |
| OJC | Otero Junior College |
| OJJC | Osaka Jogakuin Junior College |
| OLC | Oglala Lakota College |
| OLGC | Our Lady of Guadalupe Colleges |
| OLLC | Our Lady of Lourdes College |
| OLMC | Our Lady of Mercy College |
| OLR | Our Lady of the Rosary College |
| OMAC | Oriental Martial Arts College |
| OMSC | Occidental Mindoro State College |
| OPC | Ontario Police College |
| ORCA | Ocean Research College Academy |
| ORNC | Old Royal Naval College's |
| OSEC | Oxford Schools Early College |
| OSFC | Oldham Sixth Form College |
| OTBC | On The Ball College |
| OTC | Ogeechee Technical College |
| OTC | Ohio Technical College |