The Collaborative International Dictionary of English v.0.48:

Doucker \Douck"er\, n. [From aouck, for duck. See Duck, v. t.]
   (Zool.)
   A grebe or diver; -- applied also to the golden-eye, pochard,
   scoter, and other ducks. [Written also ducker.] [Prov.
   Eng.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ducker \Duck"er\, n.
   1. One who, or that which, ducks; a plunger; a diver.
      [1913 Webster]

   2. A cringing, servile person; a fawner.
      [1913 Webster]