| OR | a logical binary relation that is true if any argument is true, and false otherwise; [o]estrogen rec... |
|---|---|
| ORN | operating room nurse; orthopedic nurse |
| ORT | object relations technique; operating room technician; oral rehydration therapy |
| PAR | participating provider; passive avoidance reaction; perennial allergic rhinitis; photosynthetically ... |
| PARR | postanesthesia recovery room |