\Trea"tise\, n. [OE. tretis, OF. treitis, traitis, well
made. See {Treat}.]
1. A written composition on a particular subject, in which
   its principles are discussed or explained; a tract.
   --Chaucer.
         He published a treatise in which he maintained that
         a marriage between a member of the Church of England
         and a dissenter was a nullity.        --Macaulay.
Note: A treatise implies more form and method than an essay,
      but may fall short of the fullness and completeness of
      a systematic exposition.
2. Story; discourse. [R.] --Shak.