The crossword solution for the term 'Tissue Box Word' is PLY, which is a three letter word. PLY is a term used to describe the number of layers or strands in a material. It is commonly used to refer to the number of layers in paper, fabric, and wood. Plywood is an example of a material made up of multiple layers of wood glued together. PLY is also used to refer to the number of strands in yarn or thread.