Note that there are several window managers around that have "fvwm" in their name. In the past, version 2.x of fvwm was commonly called fvwm2 to distinguish it from the former version 1.x (fvwm or even fvwm1). Since version 1.x has been replaced by version 2.x a long time ago we simply call version 2.x and all versions to come, fvwm, throughout this document, and the executable program is named fvwm. There is an fvwm offspring called fvwm95, it is mostly a patched version of fvwm-2.0.43. The main goal of fvwm95 was to supply a Windows 95 like look and feel. Since then, fvwm has been greatly enhanced and practically all fvwm95 features can be achieved by fvwm.
( fvwm.man.descriptionより )
fvwmの名前は[ F? Virtual Window Manager ]から、[ F ]については開発者自身が忘れてしまった為、不明である。