| Abbreviation | Definition |
|---|---|
| OPSA | Oklahoma Private School Association |
| OPSB | Orleans Parish School Board |
| OPSB | Ouachita Parish School Board |
| OPSB | Ouachita Parish School Board, Monroe, Louisiana |
| OPSBA | Ontario Public School Boards' Association |
| OPSD | Ogallala Public School District |
| OPSS | Orchard Park Secondary School |
| OPSS | Ouachita Parish School System |
| OQS | OttauQuechee School |
| OQSA | Oxfordshire Quality Schools Association (UK) |
| ORES | Organization Of Rural Elementary Schools |
| ORHS | Oak Ridge High School |
| ORHS | Otay Ranch High School |
| ORHS | Oxford Regional High School |
| ORHS | Oyster River High School |
| ORMS | Oak Run Middle School |
| ORMS | Oklahoma Road Middle School |
| ORMS | Oyster River Middle School |
| OROS | Organization of Rural Oklahoma Schools |
| ORS | One Room Schoolhouse |