OPL
- Luxembourg Philharmonic Orchestra
- Oakville Public Library
- Oceanic Pro League
- Omaha Public Library
- Oman Professional League
- One-person library
- Ontario Premier League
- Open Programming Language
- Open Publication License
- Operating lease
- Optical path length
- Optimization Programming Language
- Oshawa Public Library
- Ottawa Public Library
- Struggling People's Organization
- Yamaha (manufacturer)
- Yamaha OPL
- Yamaha YM3526
- Yamaha YM3812
- Yamaha YMF262
- Yamaha YMF278