| Abbreviation | Definition |
|---|---|
| OS | Optimize for Size |
| OS/2 | Operating System/2 |
| OS/360 | IBM 360 operating system (1960s) |
| OSAS | Open Systems Accounting Software |
| OSC | Obix Source Code |
| OSC | Optimized Soft Cancellation |
| OSC | Optimized Soft Citeseer |
| OSCAR | Online Software Catalog And Reference |
| OSCI | Oberon System and Compiler Implementation |
| OSCI | Online Services Computer Interface |
| OSCON | Open Source Convention |
| OSCR | Open Source Course Reserve |
| OSD | Open Software Description |
| OSD | Open Software Distribution |
| OSD | Operating System Deployment |
| OSD | Operational Support Document |
| OSD | Outside Source Design |
| OSDR | Outdoor Software Defined Radio |
| OSE | Open Servlet Engine |
| OSEF | Oriented Software Engineering Flow |