| Abbreviation | Definition |
|---|---|
| OSC | Other Side of Creativity |
| OSCAR | Open School Courses And Resources |
| OSCAR | Our School Can Achieve Results |
| OSCAR | Our School Cares About Reading |
| OSCAR | Our School Cares About Recycling |
| OSCAR | Our School Community Actively Recycling |
| OSD | Occupational Skill Development |
| OSD | Office of Scholar Development |
| OSEF | Ocean Springs Education Foundation |
| OSEP | Office of Special Education Programs |
| OSER | Ocean Sciences Educators Retreat |
| OSER | Open Source Educational Robotics |
| OSERS | Office of Special Education and Rehabilitative Services |
| OSET | Ontario Special Education Tribunals |
| OSH | One Semester Hour |
| OSHCC | Outside School Hours Care Center |
| OSHCCs | Outside-School-Hours Care Centers |
| OSHE | of the Secretary of Higher Education |
| OSHE | Office of the Secretary of Higher Education |
| OSIM | Open Society Institute Montenegro |