\Wa"ter*mark`\, n.
1. A mark indicating the height to which water has risen, or
   at which it has stood; the usual limit of high or low
   water.
2. A letter, device, or the like, wrought into paper during
   the process of manufacture.
Note: ``The watermark in paper is produced by bending the
      wires of the mold, or by wires bent into the shape of
      the required letter or device, and sewed to the surface
      of the mold; -- it has the effect of making the paper
      thinner in places. The old makers employed watermarks
      of an eccentric kind. Those of Caxton and other early
      printers were an oxhead and star, a collared dog's
      head, a crown, a shield, a jug, etc. A fool's cap and
      bells, employed as a watermark, gave the name to
      foolscap paper; a postman's horn, such as was formerly
      in use, gave the name to post paper.'' --Tomlinson.
3. (Naut.) See {Water line}, 2. [R.]