FSW may stand for:
- Fanhui Shi Weixing, a series of recoverable satellites from the Chinese space program
- Faso Airways airline (ICAO code)
- Feet of sea water, a designation of both depth and pressure in scuba diving
- As a unit of pressure, 33 fsw is approximately one atm
- Fellowship of Southern Writers
- Female sex workers
- Flash freeze warning, in Specific Area Message Encoding
- Forward-swept wings, a type of aircraft configuration
- Fox Sports World
- Free State Wyoming
- Freestyle walking
- Freestyle wrestling
- Friction stir welding
- Full Spectrum Warrior, a video game