FDL is an abbreviation for:
- Federation of Italian Liberals, more commonly known in Italian as Federazione dei Liberali Italiani
- Fiber Delay Line
- File Definition Language, in OpenVMS
- Film Digital Line, Model FDL60 and FDL90 Telecine from Robert Bosch GmbH, Fernseh Div.
- Firedoglake, a political blog
- Fleur-de-lis
- Flexible and Distributed Learning see e-learning
- Flexor digitorum longus muscle
- Flow Definition Language
- Fond du Lac, several places in the United states and Canada
- Food, Drug, and Liquor, as in retail channels for selling alcohol beverages.
- Foresight Desktop GNU/Linux
- Fossa dei Leoni
- Frame Display Lists, an aspect of the Gecko API
- GNU Free Documentation License
- US Airforce Flight Dynamics Laboratory
FDL can also be in reference to:
- The GE FDL series of diesel engines