Source : Webster's Revised Unabridged Dictionary (1913)

Duck \Duck\, n. [OE. duke, doke. See {Duck}, v. t. ]
   1. (Zool.) Any bird of the subfamily {Anatin[ae]}, family
      {Anatid[ae]}.

   Note: The genera and species are numerous. They are divided
         into {river ducks} and {sea ducks}. Among the former
         are the common domestic duck ({Anas boschas}); the wood
         duck ({Aix sponsa}); the beautiful mandarin duck of
         China ({Dendronessa galeriliculata}); the Muscovy duck,
         originally of South America ({Cairina moschata}). Among
         the sea ducks are the eider, canvasback, scoter, etc.

   2. A sudden inclination of the bead or dropping of the
      person, resembling the motion of a duck in water.

            Here be, without duck or nod, Other trippings to be
            trod.                                 --Milton.

   {Bombay duck} (Zo["o]l.), a fish. See {Bummalo}.

   {Buffel duck}, or {Spirit duck}. See {Buffel duck}.

   {Duck ant} (Zo["o]l.), a species of white ant in Jamaica
      which builds large nests in trees.

   {Duck barnacle}. (Zo["o]l.) See {Goose barnacle}.

   {Duck hawk}. (Zo["o]l.)
      (a) In the United States: The peregrine falcon.
      (b) In England: The marsh harrier or moor buzzard.

   {Duck mole} (Zo["o]l.), a small aquatic mammal of Australia,
      having webbed feet and a bill resembling that of a duck
      ({Ornithorhynchus anatinus}). It belongs the subclass
      Monotremata and is remarkable for laying eggs like a bird
      or reptile; -- called also {duckbill}, {platypus},
      {mallangong}, {mullingong}, {tambreet}, and {water mole}.
      

   {To make ducks and drakes}, to throw a flat stone obliquely,
      so as to make it rebound repeatedly from the surface of
      the water, raising a succession of jets

Buffel duck \Buf"fel duck\ (b[u^]f"f[e^]l d[u^]k`). [See
   {Buffalo}.] (Zo["o]l.)
   A small duck ({Charitonetta albeola}); the spirit duck, or
   butterball. The head of the male is covered with numerous
   elongated feathers, and thus appears large. Called also
   {bufflehead}.