| Abbreviation | Definition |
|---|---|
| OQV | Operational Quality Verification |
| OQZ | Operational Quality: Zilch |
| OR | Operation Research |
| OR | Operational Right |
| OR | Operations Requirement |
| OR | Operations Review |
| OR | Operations Room |
| OR | Outer Roll |
| OR | Oxygen Relief |
| ORB | ORBit |
| ORB | Orbit, Orbital, Orbiter |
| ORB | Order |
| ORCHIS | Oak Ridge Computerized Hierarchical Information System |
| ORD | Operational Ready Data |
| ORD | Orbital Requirements Document |
| ORD | ORDer |
| ORDC | Orbiter Data Reduction Center |
| ORE | On-Orbit Repair Experiment |
| ORF | Orifice |
| ORG | ORGanization |