Source : Webster's Revised Unabridged Dictionary (1913)

Dunker \Dun"ker\, n. [G. tunken to dip.]
   One of a religious denomination whose tenets and practices
   are mainly those of the Baptists, but partly those of the
   Quakers; -- called also {Tunkers}, {Dunkards}, {Dippers},
   and, by themselves, {Brethren}, and {German Baptists}.

   Note: The denomination was founded in Germany in 1708, but
         after a few years the members emigrated to the United
         States.

   {Seventh-day Dunkers}, a sect which separated from the
      Dunkers and formed a community, in 1728. They keep the
      seventh day or Saturday as the Sabbath.