Virtual Device Driver(VxD) A {device driver} under {Windows 3.x}/{Windows 95} running as part of the {kernel} and thus having access to the memory of the kernel and all running processes as well as raw access to the hardware. VxD's usually have the {filename extension} .386 under Windows 3.x and .vxd under Windows 95. VxD's written for Windows 3.x can be used under Windows 95 but not vice versa. (1997-02-27)