| NRSA | National Research Service Award [of NIH] |
|---|---|
| OBS | obesity; obstetrical service; organic brain syndrome |
| OHS | obesity hypoventilation syndrome; occipital Horn syndrome; occupational health service; ocular histo... |
| OPS | operations; optical position sensor; osteoporosis-pseudolipoma syndrome; outpatient service; outpati... |
| PAS | para aminosalicylate; Parent Attitude Scale; patient administration system; patient appointments and... |