Source : Webster's Revised Unabridged Dictionary (1913)

Retting \Ret"ting\, n.
   1. The act or process of preparing flax for use by soaking,
      maceration, and kindred processes; -- also called
      {rotting}. See {Ret}. --Ure.

   2. A place where flax is retted; a rettery. --Ure.

Source : WordNet®

ret
     v : of flax, hemp, or jute, so as to promote loosening of the
         fibers form the woody tissue
     [also: {retting}, {retted}]

retting
     See {ret}