RightClick the term used for clicking the right-hand mouse button. This is differentiated from the usual Click (which is the left-hand mouse button). It is often used bring up a context sensitive menu. For example, if you RightClick on a file in the ROXfiler it will bring up the menu of things you can do with that particular file, also considering its type. Where as if you RightClick on the Desktop and you will get the PuppyMenu.
The mouse can be configured with the left and right button functions switched, if you are left-handed or if that's your preference.