| Abbreviation | Definition |
|---|---|
| OPCI | Out of Parameter Circuit Interrupters |
| OPF | Optimal Power Flow |
| OPGW | Optical Ground Wire |
| OPL | Optically Pumped Laser |
| OPLS | Optimized Potentials For Liquid Simulations |
| OPM | Optical Power Meter |
| OPPM | Overlapping Pulse Position Modulation |
| OPSE | Optically Pumped Stimulated Emission |
| OPSK | Optimum Phase-Shift Keying |
| OPSUM | OPerational SUMming amplifier |
| OPT | Optical Process Test |
| OP-TDLAS | Open Path Tunable Diode Laser Absorption Spectroscopy |
| OPU | Optical Pick-up Unit |
| OPUS | Oscillating Pick Up System |
| OPW | Orthogonalized Plane Wave |
| OQE | Optical and Quantum Electronics |
| OR | logical OR |
| ORB | Object Request Broker |
| OREC | Ohio Rural Electric Cooperatives |
| OREC | rural electric cooperatives |