| Abbreviation | Definition |
|---|---|
| OPER | Operations, Operate, Operator |
| OPF | Orbiter Processing Facility |
| OPFC | Orbiter Preflight Checklist |
| OPGUID | Optimum Guidance (Technique) |
| OPI | Orbiter Payload Interrogator |
| OPIDF | Operational Planning Identification File |
| OPIS | Orbiter Prime Item Specification |
| OPL | Open Problem List |
| OPL | Operational |
| OPLF | Orbiter Processing and Landing Facility |
| OPNS | Operational Phase |
| OPNS | OPeratioNS phase |
| OPO | Orbiter Projects Office |
| OPOV | Oxidizer Preburner Oxidizer Valve |
| OPP | Opportunity |
| OPP | Opposite |
| OPPAR | Orbiter Project(s) Parts Authorization Request |
| OPPL | Orbiter Project Parts List |
| OPR | Operations Planning Review |
| OPR | Orbiter/Payload Recorder |