| Abbreviation | Definition |
|---|---|
| OPD | Online Professional Development |
| OPEC | Organization of the Petroleum Exporting Countries |
| OPEI | Outdoor Power Equipment Institute |
| OPFA | Ontario Professional Foresters' Association |
| OPLC | Oklahoma Prevention Leadership Committee |
| OPLF | Ohio Preservation Loan Fund |
| OPLM | Office of Publications and Logistics Management |
| OPPA | Ohio Promotional Products Association |
| OPS | Ophthalmic Photographers' Society |
| OPSA | Association for Office Professionals of South Africa |
| OPSC | Osteopathic Physicians and Surgeons of California |
| OPSM | Optical Prescription Spectacle Makers |
| OPSO | Osteopathic Physicians and Surgeons of Oregon |
| OPSS | Optics and Photonics Society of Singapore |
| OPTA | Ohio Physical Therapy Association |
| OPTA | Oklahoma Physical Therapy Association |
| OPTA | Organic Producers Trade Association |
| OPTA | Orthotic Prosthetic Technological Association |
| OPTMQ | Ordre Professionnel des Technologistes Medicaux du Quebec |
| ORA | Ontario Rifle Association |