| Abbreviation | Definition |
|---|---|
| SEF | Sealift Enhancement Feature |
| SEFA | Strong Electrostatic Forces of Attraction |
| SEG | Segment |
| SEG | Special Escort Group |
| SEHS | Special Events For Homeland Security |
| SEI | Software Engineering Institute |
| SEI | Space Exploration Initiative |
| SEI | Specific Emitter Identification |
| SEI | System Engineer and Integrator |
| SEICAP | Space-Enhanced Intel CAPabilities |
| SEIP | Systems Engineering and Implementation Plan |
| SEIT | Space Environmental Impacts Tool |
| SEK | Spezialeinsatzkommandos |
| SEKP | Single Engagement Kill Probability |
| SEL | REL Selective Release |
| SEL | Senior Enlisted Leader |
| SEL | Software Engineering Laboratory |
| SELC | Sierra Expeditionary Logistics Center |
| SELCOM | Select Committee |
| SELRES | Selected Reserve |