"layer," 1470, from M.Fr. pli
"a fold" (13c.), from O.Fr. ploi
(12c.), from stem of ployer
) "to bend, to fold," from L. plicare
"to fold, lay" see ply
(v.)). Now mainly in plywood
(1907), which is called that because the layers are so arranged that the grain of one runs at right angles to that of the next.