| Acronym | Definition |
|---|
| ECSI | Environmental Cleanup Site Information (Oregon) |
| ECSI | Electronic Control Security, Inc. (est. 1976; Clifton, NJ) |
| ECSI | Editorial Committee of the Swedish Institutes (various locations) |
| ECSI | European Customer Satisfaction Index |
| ECSI | Electronic Chips & Systems Design Initiative (est. 1993) |
| ECSI | European Centre for Strategic Innovation |
| ECSI | Educational Computer Systems Incorporated (student loans billing) |
| ECSI | Export Cargo Shipping Instruction |
| ECSI | Études, Conseils et Solutions Informatiques (French: Studies, Consulting and Information Technology Solutions; New Caledonia) |
| ECSI | East Coast of the South Island (New Zealand) |
| ECSI | EarthKeeper Center for Self Improvement |
| ECSI | Evidence Consulting Services International, LLC (Boca Raton, FL) |
| ECSI | Early Childhood Systems Initiative |