| Abbreviation | Definition |
|---|---|
| OFI | Opportunity For Improvement |
| OFK | Official Flight Kit |
| OFK | Optical Flight Kit |
| OFM | Original Equipment Manufacturer |
| OFP | Orbiter Flight Program |
| OFS | Orbital Flight System |
| OFS | Orbiter Functional Simulator |
| OFT | Orbital Flight Test |
| OFTDS | Orbital Flight Test Data System |
| OFTM | On-Orbit Flight Technique Meeting |
| OFTR | Orbital Flight Test Requirement |
| OG | Outer Gimbal (Roll) |
| OG | Oxygen Gage |
| OG | Zero Gravity |
| OGA | Outer Gimbal Angle |
| OGA | Outer Gimbal Axis |
| OGE | Operating Ground Equipment |
| OGMT | Orbiter Greenwich Mean Time |
| OGS | Outer Glideslope |
| OGS | Oxygen Generation System |