In the term 'plywood', what does the 'ply' refer to?

In the term 'plywood', the 'ply' specifically refers to the layers or laminate sheets that make up the material. Plywood is constructed by bonding together multiple thin layers of wood veneers, known as plies, with adhesive. These layers are typically arranged with their grain direction alternating, which enhances the strength and stability of the final product, minimizing issues like warping or splitting that can occur with solid wood. This layered structure is key to its durability and versatility in construction and manufacturing applications, as it combines the benefits of different wood layers into one composite material.