| Abbreviation | Definition |
|---|---|
| SMSCC | Shuttle Mission Simulator Computer Complex System |
| SMSI | Standard Manned Space Flight Initiator |
| SMSI | Standard Manned Space Flight Initiator (see NSI-I) |
| SMT | Selective Message Transaction |
| SMT | Surface Mount Technology |
| SMTAS | Shuttle Model Test and Analysis System |
| SMTF | Shuttle Mission Training Facility |
| SMTP | Simple Mail Transfer Protocol |
| SMU | Soft Mockup |
| SMU | Soft Mock-Up |
| SMU | Speaker/Microphone Unit |
| SMVP | Shuttle Master Verification Plan |
| SMVRD | Shuttle Master Verification Requirements Document |
| SMW | Standard Materials Worksheet |
| SMY | Solar Maximum Year |
| SN | Solar Network |
| SN | Space Network |
| S-N | Stress Number |
| SNF | System Noise Figure |
| SNIS | Space Network IP (Internet Protocol) Services |