| Acronym | Definition |
|---|
| EI | Employment Insurance |
| EI | Ireland |
| EI | Emotional Intelligence |
| EI | Educational Institute |
| EI | Early Intervention (special education) |
| EI | Environmental Impact |
| EI | Engineering Index |
| EI | Earth Institute (Columbia University) |
| EI | European Integration |
| EI | Employment Insurance Program (Canadian Federal Formerly Unemployment Insurance, UI) |
| EI | Environmental Illness |
| EI | Enrique Iglesias (Latin music artist) |
| EI | Energy Institute (London, UK professional body for energy, oil & gas) |
| EI | Education International |
| EI | Engineering Information (rigidity measure) |
| EI | Aer Lingus (Airline Identification Code) |
| EI | Environmental Information (various organizations) |
| EI | Eat It |
| EI | Electronic Imaging |
| EI | Emissions Inventory |
| EI | Educational Insights |
| EI | Electron Ionization |
| EI | Election Integrity (election advocacy group) |
| EI | Entertainment Industry |
| EI | Electron Impact (ionization) |
| EI | Exposure Index (cinematography) |
| EI | Every Issue |
| EI | East Indies |
| EI | Electron-Impact Ionization |
| EI | Enterprise Integration |
| EI | Equine Influenza |
| EI | Exercise Information |
| EI | Esercito Italiano (Italian Army) |
| EI | Employee Involvement |
| EI | Energy Intensity |
| EI | External Interface(s) |
| EI | Employee Information |
| EI | External Input |
| EI | Electromagnetic Induction |
| EI | Environmental Institute (University of Alabama) |
| EI | Energy Index |
| EI | End Item |
| EI | Economic Ideas |
| EI | Engineer Intern |
| EI | Eugene Island |
| EI | Extended Information |
| EI | Extraterrestrial Intelligence |
| EI | Earth Interactions |
| EI | Extreme Ironing (sport) |
| EI | Electrical Instrumentation |
| EI | Entry Interface (NASA) |
| EI | Electronic Interface |
| EI | Emotionally Impaired |
| EI | Exercise Item (US DoD) |
| EI | Error Indicator |
| EI | Electrical Interface |
| EI | Enable Interrupt (assembly language instruction) |
| EI | Engineering Investigation |
| EI | Encryption Item (trade) |
| EI | Expectations Index |
| EI | Effectiveness Index |
| EI | Esquerra Independentista (Catalan countries) |
| EI | Engineering-Installation |
| EI | Engineering Instructions |
| EI | Expansion Index (soil) |
| EI | Expansion Interface |
| EI | Exposure Investigation |
| EI | Enemy Infantry (WWIIOnline game) |
| EI | Extensor Indicis |
| EI | External Integration |
| EI | Evening Independent (St Petersburg, FL newspaper) |
| EI | Event Interval |
| EI | Eppley Institute |
| EI | Engineering Interoperability |
| EI | Electrical Inspectorate |
| EI | Etiquette International |
| EI | Études Intégrées (French: Integrated Studies) |
| EI | Enterprise and Innovations |
| EI | Ephemeris Improvement |
| EI | Execution Indexing |