FDL
- Federal Depository Library
- Federation of Liberals
- Firebase
- Firedoglake
- Fleur-de-lis (disambiguation)
- Flexor digitorum longus
- Florida Democratic League
- Fond du Lac (disambiguation)
- Fossa dei Leoni
- Four Door Lemon
- GE FDL
- GNU Free Documentation License
- OpenVMS
- Record Management Services
- USNS Lynn (T-AG-182)
- United States Air Force Flight Dynamics Laboratory