FSL may refer to:
Language
Other uses
- Fast Simplex Link, a soft microprocessor bus
- Five Schools League, a Northeast United States prep school athletics league
- Fleet Support Limited, a British logistics company
- Florida State League, an American minor baseball league
- Fluid Science Laboratory, on the International Space Station
- FMRIB Software Library
- FM FSL, a rifle
- Folger Shakespeare Library in Washington, D.C., United States
- Forecast Systems Laboratory of the United States National Oceanic and Atmospheric Administration
- Fox Sports Live, an American television program
- Fraternitas Scintilla Legis, a Philippine fraternity
- Freescale Semiconductor, an American semiconductor manufacturer
- Free-space loss
- Friends' School, Lisburn, in Northern Ireland
- Function-spacer-lipid construct
