4Dwm is a window manager normally used on Silicon Graphics workstations running IRIX. 4Dwm is derived from the older mwm window manager and uses the Motif widget toolkit on top of the X Window System found on most Unix systems.
4Dwm on IRIX was one of the first default graphical user interface desktops to be standard on a particular Unix computer system. Other X window managers that mimic the 4Dwm look and feel exist, such as 4Dwm theme for IceWM and 5Dwm. 4Dwm refers to "Fourth dimension window manager" and has no relation to dwm.