| Acronym | Definition |
|---|
| FSI | Foreign Service Institute |
| FSI | Fluid Structure Interaction |
| FSI | Free Swelling Index (coal) |
| FSI | Fuel Stratified Injection |
| FSI | Federazione Scacchistica Italiana (Italian Chess Federation) |
| FSI | Free Standing Insert |
| FSI | Floor Space Index |
| FSI | Flight Simulator |
| FSI | Fournisseur de Services Internet (France) |
| FSI | Federal Sources, Inc. |
| FSI | Forest Survey of India |
| FSI | Flight Safety International |
| FSI | Final-State Interaction |
| FSI | Florida Space Institute |
| FSI | Forensic Science International |
| FSI | Fellow of the Securities Institute |
| FSi | Football Streaming Info |
| FSI | FRISK Software International |
| FSI | Fishery Survey of India |
| FSI | Fédération Suisse des Organisations d'Informatique |
| FSI | Fellow of the Securities & Investment Institute |
| FSI | Food, Seed and Industrial (agriculture) |
| FSI | Forensic Science Institute (Los Angeles, CA) |
| FSI | Financial Systems Integration |
| FSI | First State Innovation (Delaware) |
| FSI | Funeral Services, Inc (Tallahassee, FL) |
| FSI | Financial Service Institution |
| FSI | Flag State Implementation Sub-Committee (IMO) |
| FSI | Functionally Significant Item |
| FSI | Federal Systems Integrator |
| FSI | Financial Statement Item |
| FSI | Fasting Glucose and Specific Insulin Levels |
| FSI | Facility Science Instrument |
| FSI | Feasibility Study Institute |
| FSI | Fraud Scheme Investigator |
| FSI | FORCEnet Services Infrastructure |
| FSI | Federazióne Svizzera Delle Organizzatióni d'Informatica |
| FSI | Federal Stock Item |
| FSI | Fire Safety International Ltd (UK) |
| FSI | Fuchs Swelling Index |
| FSI | Forestry Science Institute of Vietnam |
| FSI | Flight System Integration |
| FSI | Full Screen Interstitial (Interative Media advertising unit) |
| FSI | Fusfeld Group Inc (Framingham, MA) |
| FSI | Flanders Scientific. Incorporated |
| FSI | Failed Self Install |