| Acronym | Definition |
|---|
| EFSS | Enterprise File Sync & Share (software) |
| EFSS | Expeditionary Fire Support System (USMC) |
| EFSS | Expeditionary Force Support Squadron (US DoD) |
| EFSS | E. F. Schumacher Society (economic development; Great Barrington, MA) |
| EFSS | Europe Fermetures Sécurité Systèmes (France) |
| EFSS | Économie et Finance Sociales et Solidaires (French: Economy and Finance and Social Solidarity) |
| EFSS | English Folk Song Society (now English Folk Dance and Song Society; est. 1898) |
| EFSS | Electronic Filing and Service System (district court; Georgia) |
| EFSS | Elizabeth Fry Society of Saskatchewan (Canada) |
| EFSS | Experimental Flight Systems Section (NASA) |