| Abbreviation | Definition |
|---|---|
| SEESAC | South Eastern Europe Clearinghouse for the Control of Small Arms and Light Weapons |
| SEFEP | Smart Energy for Europe Platform |
| SEGD | SouthEastern Guide Dogs |
| SEGD | SouthEastern Guide Dogs, Inc. |
| SEGD | SouthEastern Guide Dogs, Incorporated |
| SEHC | Service Enriched Housing Continuum |
| SEI | The Seeing Eye, Inc. |
| SELDOC | South East London Doctors Cooperative |
| SELF | Solar Electric Light Fund |
| SEM | Society for Experimental Mechanics |
| SEM | Systematic Evaluation of Members |
| SEMS | Society for Engineering Management Systems |
| SERP | Society for Elimination of Rural Poverty |
| SERV | Service by Emergency Rider Volunteers |
| SERVE | Sending Experienced Retired Volunteers Everywhere |
| SESAME | Stop Educator Sexual Abuse, Misconduct, and Exploitation |
| SESI | Serviço Social da Industria |
| SETI | Search for Extra-Terrestial Intelligence |
| SETI | Search for Extra-Terrestrial Intelligence |
| SEW | The Society For Emigrant Women |