| Abbreviation | Definition |
|---|---|
| OPC | Open Process Control |
| OPEC | Organization of Petroleum Exporting Countries |
| OPFAC | Operating Facility |
| OPL | Outer Port Limit |
| OPRG | Oxygenated Fuels Program Reformulated Gasoline |
| OPS | Occupational Prayer Specialty |
| OPSS | OPerations Safety System |
| OPT | Office of Pupil Transportation |
| OPTA | Oregon Pupil Transportation Association |
| OPTL | One Person Test Lane |
| OPTO | One Person Train Operation |
| OPTP | Oregon Public Transportation Plan |
| OPTRA | Operational Training |
| OPV | Optional Piloted Vehicles |
| OQ | Operational Qualification |
| OQ | Operator Qualification |
| OQI | Outgoing Quality Improvement |
| OQR | Operator Qualification Regulations |
| OQT | Operator Qualification Testing |
| ORAR | Outdoor Recreation Access Route |