| Abbreviation | Definition |
|---|---|
| SHORAN | Short Range Navigation |
| SHOT | Space Houston On Ten |
| SHOTGUN | Space Hardware Optimization Technology Ground Users' Network |
| SHP | Shaft HorsePower |
| SHR | Significant Hazard Reduction |
| SHRD | Shroud |
| SHRD | Supplemental Heat Rejection Devices |
| SHS | Simulation Hardware System |
| SHSS | Structure and Harness Subsystem |
| SHTR | Shutter |
| SHUTDN | Shutdown |
| SI | International Systems of Units (ISU preferred) |
| SI | Kennedy Space Center Support Operations Directorate |
| SI | Scientific Instrument |
| SI | Solar Inertial |
| SI | Systeme Internationale |
| SIA | Shuttle Induced Atmosphere |
| SIA | Software Impact Assessment |
| SIA | Solar Inertial Attitude |
| SIAC | Safety Issue Assessment Center |