The Collaborative International Dictionary of English v.0.48:

Stopper \Stop"per\, n.
   1. One who stops, closes, shuts, or hinders; that which stops
      or obstructs; that which closes or fills a vent or hole in
      a vessel.
      [1913 Webster]

   2. (Naut.) A short piece of rope having a knot at one or both
      ends, with a lanyard under the knot, -- used to secure
      something. --Totten.
      [1913 Webster]

   3. (Bot.) A name to several trees of the genus Eugenia, found
      in Florida and the West Indies; as, the red stopper. See
      Eugenia. --C. S. Sargent.
      [1913 Webster]

   Ring stopper (Naut.), a short rope or chain passing through
      the anchor ring, to secure the anchor to the cathead.

   Stopper bolt (Naut.), a large ringbolt in a ship's deck, to
      which the deck stoppers are hooked.
      [1913 Webster]