| ORS | olfactory reference syndrome; oral rehydration solution; oral surgery, oral surgeon; Orthopaedic Res... |
|---|---|
| OS | left eye [Lat. oculus sinister]; occipitosacral; occupational safety; office surgery; Omenn syndrome... |
| OSM | ovine submaxillary mucin; oxygen saturation meter |
| Ox | oxygen |
| OXY, oxy | oxygen |