| Acronym | Definition |
|---|
| SEI | Software Engineering Institute (Carnegie Mellon) |
| SEI | Stockholm Environment Institute |
| SEI | Solar Energy International |
| SEI | Sumitomo Electric Industries, Ltd (Japan) |
| SEI | Structural Engineering Institute (ASCE) |
| SEI | Safety Equipment Institute |
| SEI | Service Endpoint Interface (Web coding) |
| SEI | Space Exploration Initiative |
| SEI | Sussex European Institute (UK) |
| SEI | Science Education Institute (Philippines) |
| SEI | Self Esteem Inventory (psychology) |
| SEI | Supplemental Enhancement Information |
| SEI | 7-Eleven, Inc |
| SEI | Solid Electrolyte Interface (energy storage) |
| SEI | Sony Electronics Inc. |
| SEI | Specific Emitter Identification |
| SEI | Secondary Electron Imaging |
| SEI | Sammons Enterprises Inc. (Dallas, TX) |
| SEI | Systems Engineering & Integration |
| SEI | Socio-Economic Index |
| SEI | Special Experience Identifier |
| SEI | Sociedad Española de Implantes (Spanish) |
| SEI | Service de l'Environnement Industriel (French: Industrial Environment Department) |
| SEI | Sustainable Energy Institute |
| SEI | Sensitive Ecosystem Inventory (Canada) |
| SEI | Säästva Eesti Instituut (Stockholm Environment Institute) |
| SEI | Sales Excellence Institute (University of Houston) |
| SEI | Space Engineering Institute |
| SEI | Summer Educational Institute (Art Libraries Society of North America) |
| SEI | SINOPEC Engineering Incorporation |
| SEI | Sindacato Edilizia e Industria |
| SEI | Systems and Electronics Inc. |
| SEI | Seebeck Effect Imaging |
| SEI | Scheie Eye Institute (University of Pennsylvania) |
| SEI | La Semaine de l'Education Internationale (French: International Education Week) |
| SEI | Symposium on Electrical Insulation |
| SEI | Supplementary Enhancement Information (digital TV) |
| SEI | Support Equipment Installation |
| SEI | South East Indiana |
| SEI | Select Engineering, Inc. (Tulsa, OK) |
| SEI | Survey of Emotional Intelligence |
| SEI | Stock Exchange Interface |
| SEI | Support Equipment Illustration |
| SEI | Special Emphasis Item |
| SEI | Signalétique Enseignes Industrielles (French signage company) |
| SEI | Set Interupt Status (6502/6510 assembly language) |
| SEI | Services Environmental, Inc. (Phoenixville, Pennsylvania) |
| SEI | Société d'Etudes pour l'Industrie (French: Society of Studies for Industry) |
| SEI | Science Education International (journal; International Council of Associations for Science Education) |
| SEI | Search Engine Indexer (software) |
| SEI | Science and Engineering Indicators |