The term ‘sash window’ usually refers to slippery window sash (also known as box sash windows). It is often one of the older varieties of the window, although its true origin is unknown and its invention remains a matter of dialogue.
A sash window can be a glazed part of a window or door assembly that opens for the functions of ventilation, viewing, access, correction, etc., while a window sash is that part of a window (within the frame) of hinges. It Has happened opens outside or inside.
