| Abbreviation | Definition |
|---|---|
| OPK | Ovulation Prediction Kit |
| OPL | Otolaryngology Physicians of Lancaster |
| OPLL | Ossification of Posterior Longitudinal Ligament |
| OPMT | Optometric Physicians of Middle Tennessee |
| OPN | OsteoPontiN |
| OPNS | Oakland Physician Network Services |
| OPP | Opposite |
| OPP | Ovine Progressive Pneumonia |
| OPQRST | Onset, Provokes, Quality, Radiates, Site, and Timing |
| OPS | Organic Psycho Syndrome |
| OPSC | Omni Potent Stem Cell |
| OPSE | OroPharyngeal Swallow Efficiency |
| OPSW | Office of Physician and Student Wellness |
| OPT | Ontological Paradigm Technique |
| OPT | Outpatient treatment |
| OPV | Oral Polio Vaccine |
| OPW | Optometric Physicians of Washington |
| OPZONE | Optimum Zone |
| OQ | Of Quickness |
| OR | Open Reduction |