| Abbreviation | Definition |
|---|---|
| SPUR | Space Power Unit Reactor |
| SPURT | Small Primate Un- Restrained Test |
| SPURT | SPinning Unguided Rocket Trajectory |
| SPV | Sun Probe near limb of Venus |
| SPVPF | Shuttle Payload Vertical Processing Facility |
| SQL | Squelch |
| SQM | Satellite Quality Monitor |
| SQP | Software Quality Professional |
| SQPN | Staggered Quadrature Pseudo-Noise |
| SQUID | Superconducting QUantum Interference Device |
| SQV | Sequential Blow-Off Valve |
| SQW | Square Wave |
| SR | Scan Ratio |
| SR | Shift Register |
| SR | Standard Repair |
| SR | Statement of Requirements |
| SR | Status Register |
| SR | Status Review |
| SR | SunRise |
| SR | Support Request |