Term | Explanation |
| LCS | London Controlling Section - British organisation responsible for military security, cryptanalysis and deception operations. |
| Lebensraum | Living space - Term used by the Nazis to refer to their plans for territorial expansion, particularly in the East. |
| Lend-Lease | US policy of supplying the Allies with equipment and materials in exchange for payment in kind or return of undamaged equipment following the war. |
| Lichtenstein | German airborne radar used for nightfighting. |
| Lightfoot | Operational code name for the British offensive at El Alamein - October 1942. |
| Locarno Pact | Agreement signed in 1925 by Britain, Germany, France, Belgium, Italy, Poland and Czechoslovakia, guaranteeing international boundaries and re-affirming the Treaty of Versailles. |
| Luftwaffe | The German Air Force. |