| Acronym | Definition |
|---|
| SIEC | Societa Italiana di Ecografia Cardiovascolare (Italian: Italian Society of Cardiovascular Ultrasound) |
| SIEC | Service Interacadémique des Examens et Concours (French: Interacademic Service Examinations and Competitions; est. 1982) |
| SIEC | State Interoperability Executive Council |
| SIEC | Statewide Interoperability Executive Committee (various locations) |
| SIEC | Suicide Information and Education Centre |
| SIEC | Southern Illinois Electric Cooperative (electric utility) |
| SIEC | Service des Investissements de l’Enseignement Catholique |
| SIEC | Suzhou International Exchange Center |
| SIEC | Significant Events Conference (US National Military Command Center) |
| SIEC | Southern Iowa Electric Cooperative |