Don't see that question very often. KDE stands for "K Desktop Environment", LXDE stands for "Lightweight X11 Desktop Environment", and Xfce originally stood for "XForms Common Environment". Xfce no longer uses the XForms toolkit, so they changed the acronym from XFCE to Xfce. Oh, and gnome stands for "GNU Networking Object Model Environment".
Mint 17.3 Cinnamon (Beta)