The term 'Window Projection' is a type of projection system that uses a window as the projection surface. This system is often used in commercial and educational settings, as it allows for a large image to be projected onto a wall or other surface. The crossword solution for this term is 'LEDGE, ' which refers to the LEDGE or frame that is used to hold the window in place. This LEDGE is usually made of metal or wood and is designed to securely hold the window in place while allowing for the projection of the image.