| OR | a logical binary relation that is true if any argument is true, and false otherwise; [o]estrogen rec... |
|---|---|
| OT | objective test; oblique talus; occlusion time; occupational therapist, occupational therapy; ocular ... |
| OX | optic chiasma; oxacillin; oxalate; oxide; orthopedic examination; oxytocin |
| PION | posterior ischemic optic neuropathy |
| POA | pancreatic oncofetal antigen; phalangeal osteoarthritis; preoptic area; primary optic atrophy |