| OF | occipitofrontal; open field [test]; optical fundus; orbitofrontal; osmotic fragility; osteitis fibro... |
|---|---|
| OPD | obstetric prediabetic; optical path difference; otopalatodigital [syndrome]; outpatient department; ... |
| OPS | operations; optical position sensor; osteoporosis-pseudolipoma syndrome; outpatient service; outpati... |
| OpScan | optical scanning |
| ORD | optical rotatory dispersion; oral radiation death |