| Abbreviation | Definition |
|---|---|
| OPST | Optical Packet Switch and Transport |
| OQN | Open Queuing Network |
| ORAN | Optical Regional Advanced Network |
| ORF | Open Reading Frame |
| ORION | Open Research Infrastructure for Optimizing Networks |
| ORP | Output Routing Pool |
| ORRF | Optimal Rate, Reduced Feedback |
| ORTC | Object Real-Time Communications (computer community group) |
| OS | Online Services |
| OS | Open Server |
| OS | Overhead Sending |
| OSA | Omnibus Service Authority |
| OSC | Optical Supervisory Channel |
| OSCAR | Open Source Cluster Application Resource |
| OSE | Office Server Extensions |
| OSGP | Open Smart Grid Protocol |
| OSI | Open System Interconnection |
| OSN | Original Senshi Network |
| OSPF | Open Shortest Path First |
| OSTG | Open Source Technology Group |