Window material is a term used to refer to the materials used to construct windows. GLASS is the most common window material, and is made from melted sand and other minerals. It is five letters long. CURTAIN is another window material, which is seven letters long. It is usually made of fabric and is used to cover windows for privacy or insulation. Paneglass is a nine letter window material that is a combination of GLASS and plastic. It is often used in skylights and conservatories. Sheetglass is a ten letter window material that is made from a single sheet of GLASS. It is often used in large windows and doors.