| Abbreviation | Definition |
|---|---|
| SIG | Special Integration Group |
| SIG | Special Interest Group |
| SIGACTS | significant activities |
| SIGADA | Special Interest Group for ADA |
| SIGC2 | Signal Command and Control |
| SIGCEN | Signal Center |
| SIG-D | implified Inertial Guidance Demonstration |
| SIG-D | Simplified Inertial Guidance Demonstration |
| SIGI | System Of Interactive Guidance And Information |
| SIGINT | Signal Intelligence |
| SIGINT | Signals Intelligence |
| SIGIR | Special Inspector General for Iraq Reconstruction |
| SIGNAL | System Integrating Gps To Nullify Absence And Lateness |
| SIGSEC | Signal Security |
| SII | Seriously Ill or Injured |
| SII | Special Interest Items |
| SII | Statement of Intelligence Interest |
| SII | Summary Injury Incidence |
| SIIP | Site Integration Installation Plan |
| SIIRCM | Suite of Integrated Infrared Countermeasures (Army) |