| Abbreviation | Definition |
|---|---|
| FTX | Field Training Exercise |
| FU | Fart Underwater (submarine sound) |
| FU | Fire Unit |
| FU | First User |
| FU | Foul Up |
| FUA | Federal Union Army |
| FUAC | Functional Area Code |
| FUBAR | F***ed Up Beyond All Recognition |
| FUBAR | Fouled Up By Army Regulations |
| FUC | Feasibility, Understandability, Completeness |
| FUC | Forward Unit Commander |
| FUCK | Former Ushtria Clirimtare e Kosoves (Kosovo Liberation Army) |
| FUD | Fear, Uncertainty, and Doubt |
| FUD | Field Use Designator |
| FUD | Fire Unit Display |
| FUD | First Unit Deployed |
| FUD | Fold Up Decoys |
| FUD | Frequently Used Disinformation |
| FUDS | Formerly Used Defense Sites |
| FUDS | Formerly-Used Defense Site |