| OLD | obstructive lung disease; orthochromatic leukodystrophy |
|---|---|
| OSA | obstructive sleep apnea; Office of Services to the Aging; Optical Society of America; ovarian sectio... |
| OSAS | obstructive sleep apnea syndrome |
| PVOD | pulmonary vascular obstructive disease; pulmonary veno-occlusive disease |
| ROAD | reversible obstructive airways disease |