| Abbreviation | Definition |
|---|---|
| ONL | Office of National Laboratories |
| ONL | Open Network Laboratory |
| OOML | Organic Optoelectronic Materials Laboratory |
| OOX | Oophorectomy |
| OPEL | Ocean Prediction Experimental Laboratory |
| OPG | OculoPlethysmoGraphy |
| OPIM | Other Potentially Infectious Materials |
| OPL | Ocean Physics Laboratory |
| OPL | Online Psychology Laboratory |
| OPL | Operator Performance Laboratory |
| OPL | OSHPD Preapproved Laboratory |
| OPO | Organ Procurement Organization |
| OPSL | Old Plank Sonic Laboratories |
| OQE | Objective Quality Evidence |
| ORL | Orthopaedic Research Laboratories |
| ORMC | Oak Ridges Medical Centre |
| ORNL | Oak Ridge National Laboratory |
| ORNL | Oak Ridge National Laboratory's |
| ORS | Organic Reconstruction Syrum |
| ORV | Outstanding Remarkable Value |