| Abbreviation | Definition |
|---|---|
| SEI | Sykes Enterprise Incorporated |
| SEI | Systems Evolution Inc |
| SEIL | Scotland Electronics International Ltd |
| SEIL | Steel Exchange India Ltd |
| SEK | Smith Elliott Kearns Company, LLC |
| SEL | Scale Equipment Ltd |
| SELFINA | Sero Lease and Finance Company Limited |
| SEM | Spec Epics Motors |
| SEMAC | Southeastern Minnesota Arts Council, Inc. |
| SEMI | Semiconductor Equipment Materials International |
| SEMI | Superior Electric Maintenance Interior |
| SEOSS | South East Open Source Solutions Limited |
| SEPCIN | Shell Exploration and Producing Company In Nigeria |
| SEPCIN | Shell Exploration Production Company In Nigeria |
| SEPOC | Safer Exploration Production and Operations Company |
| SERCA | Safety and Environmental Risk Consultants Australia |
| SERI | System Energy Resources Inc |
| SERNA | South East Regional Neurological Alliance |
| SES | Symantec Enterprise Solutions |
| SESC | SGN Eurisys Services Corporation |