| Abbreviation | Definition |
|---|---|
| SEB | Systems Engineering Branch |
| SEC | SECond |
| sec | Second (s preferred) |
| SEC | Secondary |
| SEC | Sequential Events Controller |
| SEC | Source Evaluation Committee |
| SECIB | Shuttle Engineering Change Implementation Board |
| SECO | Sustainer Engine Cutoff |
| SECS | Shuttle Events Control Subsystem |
| SECT | Spacelab Experiment Channel Tape |
| SECTOR | Space Exploration And Colonization Through Organized Relationships |
| SED | Space Exploration Day |
| SEDT | Spacelab Experiment Data Tape |
| SEE | Space Environments Ecovillage |
| SEE | Special Purpose End Effector |
| SEE | Standard End Effector |
| SEEDS | Space-Exposed Experiment Developed for Students |
| SEG | System Engineering Groundrule |
| SEI | Support Equipment Installation |
| SEI | System Engineering Instrumentation |