| Abbreviation | Definition |
|---|---|
| O-M | opsoclonus-myoclonus |
| OMB | Office of Management and Budget |
| OMC | Olmsted Medical Clinic |
| OMH | Office of Men's Health |
| OMJ | Osler Medical Journal |
| OMNI | Organizing Medical Networked Information |
| OMT | Oral Mucosal Transudate |
| OMT | Orthopaedic Manual Therapy |
| OMZ | Oxygen Minimum Zone |
| ON | Optic Neuritis |
| ONC | ONCology |
| ONH | Optic Nerve Hypoplasia |
| ONJ | OsteoNecrosis of the Jaw |
| ONS | Other Nervous System |
| ONT | Ontology |
| ONTO | Ontology |
| OOM | Office of Occupational Medicine |
| OOP | Out Of Plaster |
| OOR | Orphan Opioid Receptor |
| OORL | Orphan Opioid Receptor Ligand |