| MS-DOS | Microsoft Disk Operating System |
|---|---|
| NOS | network operating system; nitric oxide synthetase; non-organ-specific; not on staff; not otherwise s... |
| ONP | operating nursing procedure; orthonitrophenyl |
| OS | left eye [Lat. oculus sinister]; occipitosacral; occupational safety; office surgery; Omenn syndrome... |
| SOP | service-object pair; standard operating procedure |