Source : Webster's Revised Unabridged Dictionary (1913)

Duck \Duck\, v. t. [imp. & p. p. {Ducked}; p. pr. & vb. n.
   {Ducking}.] [OE. duken, douken, to dive; akin to D. duiken,
   OHG. t?hhan, MHG. tucken, t["u]cken, t?chen, G. tuchen. Cf.
   5th {Duck}.]
   1. To thrust or plunge under water or other liquid and
      suddenly withdraw.

            Adams, after ducking the squire twice or thrice,
            leaped out of the tub.                --Fielding.

   2. To plunge the head of under water, immediately withdrawing
      it; as, duck the boy.

   3. To bow; to bob down; to move quickly with a downward
      motion. `` Will duck his head aside.'' --Swift.