If wood, stone, or metal is fretted, it has been cut or shaped into busy, repeating patterns — often with gaps you can see through, or with lines that cross like a net. Old churches, palace ceilings, and wooden screens are often described this way: the decoration itself is the point. It is a fairly literary or specialist word; a carpenter might just say the piece is cut with a pattern. Though actually, English also uses fretted for a guitar or similar instrument that has metal bars on the neck, and for someone who has been worrying. Those are other lives of the spelling. This entry is only the decorative one: patterned by cutting.