| Abbreviation | Definition |
|---|---|
| OPRR | Object Property Role Relationship |
| OPSW | Ontology Pattern for the Semantic Web |
| OQ | Output Quality |
| OQG | Output Queue Grant |
| OR | logical OR (programming, IC design) |
| OR | Originator / Recipient |
| ORCA | Open Repository Case API (Application Programmer Interface) |
| ORI | Originating Response Indicator |
| ORO | Original Reusable Object |
| ORT | Object Relations Technique |
| OS | Open System |
| OS2 | Operating System/2 |
| OSA | Office Systems Architecture |
| OSA | Open Scripting Architecture |
| OSA | Open Service Access |
| OSA | Open Standard Architecture |
| OSA | Open System Architecture |
| OSB | Option Select Button |
| OSB | Output |
| OSC | Ohio Supercomputer Center |