| Abbreviation | Definition |
|---|---|
| OPLK | Ontology Of Professional Legal Knowledge |
| OPMI | Ontology of Precision Medicine and Investigation |
| OPN | Opinion |
| OPNET | Olympic Peninsula Narcotics Enforcement Team |
| OPO | Owen, Patterson, & Owen |
| OPP | Other Peoples Property |
| OPPA | Ontario Political Payoff Act |
| OPTICS | Oscura Peak Tracker Investigation and Comparison Series |
| OPUE | Occupant Protection Usage and Enforcement |
| OPUE | Occupant Protection Usage Enforcement |
| OPUS | Offender Population United System |
| OQE | Objective Quality Evidence |
| ORB | Ontario Review Board |
| ORC | Organized Retail Crime |
| ORCA | Organized Retail Crime Association |
| ORJ | Office of Reentry and Justice |
| ORJ | Office of Restorative Justice |
| OS | the Opposite Sex |
| OSAC | Oxy Sexual Assault Coalition |
| OSB | Oregon State Bar |