Term | Explanation |
| Fall Gelb | Case Yellow |
| Fall Gruen | Case Green |
| Fall Rot | Case Red |
| Fall Weiss | Case White |
| FCNL | French Comittee of National Liberation. |
| Feldgendarmerie | German military police. |
| Feldgrau | Field Grey - term used to describe the ordinary German soldier - from the colour of his tunic. |
| Felix | Operational code name for the German plan to capture Gibraltar in 1941. |
| FFI | French Forces of the Interior. |
| FH | Fremde Heere - German intelligence evaluation service. |
| FHO | Fremde Heere Ost - German intelligence evaluation service - eastern section. |
| FHW | Fremde Heere West - German intelligence evaluation service - western section. |
| Fischfang | Fish Trap - Operational code name for the German counter attack on the Allied beachead at Anzio in February 1944. |
| Flash | Code name for the assassination attempt on Hitler by the Schwarze Kapelle in March 1943 - where a bomb was placed on Hitler's aircraft. |
| Flintlock | Operational code name for the US invasion of the Marshall Islands in January 1944. |
| Forager | Operational code name for the US invasion of the Mariana Islands in June 1944. |
| Forschungsamt | The intelligence service of the Luftwaffe. |
| Fortitude | Operational code name for the Allied deception operations prior to the invasion of Normandy. |
| FUSAG | First US Army Group - a fictitious army group under the command of General Patton which appeared to be based in south-east England prior to the Normandy landings and was intended to give the impression that the Allies were due to invade France via the Pas de Calais. |