| Abbreviation | Definition |
|---|---|
| OPTG | Online Pathway To Graduation |
| OPTIONS | Office Professional Training for Information Organization and Networking Skills |
| OPUS | Optimising Public Understanding of Science |
| OQE | Organization for Quality Education |
| OREA | Oklahoma Retired Educators Association |
| OREO | Ontario Rabbit Education Organization |
| ORF | Opening Reading Frame |
| ORF | Oral Reading Fluency |
| ORG | Organizational Research Group |
| ORI | Operation Respect, Inc. |
| ORLA | Olympia Regional Learning Academy |
| ORM | Possibly Dangerous, subject of possible litigation! Over-represented minority |
| ORMT | Ontario Registered Music Teachers |
| ORMTA | Ontario Registered Music Teachers' Association |
| ORS | Occupant Restraint System |
| OS | Old School |
| OS | Orientation Sessions |
| OSA | Oshkosh Student Association |
| OSAO | Overseas Students' Affairs Office |
| OSC | Old School Crew |