Dictionary.net

A menu which appears in response to auser action (typically a mouse click) and whose contents aredetermined by which application window was clicked or hasthe input focus.Most GUIs use a secondary mouse button (right or middle) tocall up a context-sensitive menu as the primary mouse buttonis normally used to interact with objects which are alreadyvisible.The context-sensitive menu often contains functions that arealso available in a menu bar but the context-sensitive menuprovides quick access to a subset of functions that areparticularly relevant to the window area clicked on.The RISC OS WIMP uses only context-sensitive menus (alwaysinvoked using the middle mouse button). This saves screenspace and reduces mouse movement compared to a menu bar.