| Abbreviation | Definition |
|---|---|
| OAT | O-acetyltransferase |
| OAT | Object Alternation Test |
| OAT | oligoasthenoteratozoospermia |
| OAT | open artery trial |
| OAT | oral anticoagulation therapy |
| OAT | organic anion transporter |
| OAT | ornithine acetyltransferase |
| OAT | ornithine aminotransferase |
| OAT | osteoarticular tuberculosis |
| OAT | Out of Area Transfer |
| OAT | Out of Area Treatment(formerly ECRextracontractual referral) |
| OAT | Out of Area Treatment(formerly ECR–extracontractual referral) |
| OAT | oxygen atom transfer |
| OBC | optimum bactericidal concentration |
| OBD | occupied bed day |
| OBD | opioid bowel dysfunction |
| OBD | organic brain disease |
| OBS | obliterative bronchiolitis syndrome |
| OBS | obstetric service |
| OBS | obstruction |