FSL

FSL may refer to:

Language

 * Filipino Sign Language
 * Finnish Sign Language
 * French Sign 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