| SEIS | Isabel Maria, Ecuador 
| Others |
| SEIS | Seed Enterprise Investment Scheme
| Others |
| SEIS | Seismic Experiment for Interior Structure
| Others |
| SEIS | Shared Environmental Information System
| Others |
| SEIS | Single European Information Space
| Others |
| SEIS | Software Engineering and Information Systems
| Others |
| SEIS | Software Engineering in Society
| Others |
| SEIS | Special Education in Institutional Settings
| Others |
| SEIS | Special Education Information System
| Others |
| SEIS | Submarine Escape Immersion Suit
| Others |
| SEIS | Supplemental Environmental Impact Statement
| Others |
| SEIS | Supplementary Environmental Impact Statement
| Others |