WIMP stands for "window, icon, menu, pointers" and is a term frequently used in HCI (Human Computer Interaction), to describe a minumum set of requirements for GUI.
The Amstrad CPC, as a low-cost 8-bit computer did not offer a native GUI. However, several third-party efforts were made to produce a graphical interface to make computer use easier, with varying degrees of success. Proliferation of GUIs on the CPC was hampered by the fact that a major component, the mouse, did not come cheap at the time, so few applications were developed for them.