Waterlandian

from The Collaborative International Dictionary of English v.0.48

Waterlander \Wa`ter*land"er\, Waterlandian \Wa`ter*land"i*an\n.
   (Eccl. Hist.)
   One of a body of Dutch Anabaptists who separated from the
   Mennonites in the sixteenth century; -- so called from a
   district in North Holland denominated Waterland.
   [1913 Webster]