Thickness of wood or paper

PLY

Consider the term used for layers in materials like wood or cardboard.

The clue "Thickness of wood or paper" hints at "ply," which refers to a layer or thickness in materials like wood (as in plywood) or paper. It’s a straightforward definition where "ply" directly describes the number of layers or the thickness itself. No wordplay is involved—just a simple, direct connection between the clue and the answer.