Ply, Pli, Plies or Plying may refer to:
- Ply (game theory), a turn in game play
- PLY (file format) or Polygon File Format
- Plying, a spinning technique to make yarn
- Plies (rapper), American rapper
- Pli, an academic journal
- Ply, a layer of paper or wood, such as with toilet paper, tissue paper, paper towels or plywood
- PLY, an implementation of the yacc parsing tool for the Python programming language
- Tire ply, a layer of cords embedded in the rubber of a tire