ply1

noun (plural plies)

• 1a thickness or layer of a folded or laminated material.
• [usually in combination] a strand of yarn or rope: [as modifier]:four-ply yarn
• the number of layers or strands of which something is made:the yarn can be any ply from two to eight
• [usually in combination] a reinforcing layer of fabric in a tire: [as modifier]:a six-ply whitewall tire

• 2short for plywood.

• 3(in game theory) the number of levels at which branching occurs in a tree of possible outcomes, typically corresponding to the number of moves ahead (in chess strictly half-moves ahead) considered by a computer program.
• a half-move (i.e., one player’s move) in computer chess.