The term 'IMAGE ON A SCREEN' can be represented by the four-letter word 'ICON'. An ICON is a small graphical representation of an object, action, or idea. It is typically used to help users navigate computer programs and websites. Icons are often used to represent common functions, such as saving a file or printing a document. They are also used to represent objects, such as a folder or a printer. Icons are usually displayed on a computer screen, making them easy to identify and use.