n. A cylinder of wood, plastic, cardboard, or other material on which wire, thread, or string is wound.n. The amount of wire, thread, or string wound on such a cylinder.n. Something similar to such a cylinder in shape or function.n. A reel for magnetic tape.v. To wind or be wound on or off a spool.v. To store (data sent to a printer) in a buffer, allowing the program that sent the data to the printer to resume its normal operation.