D defs.my
Entry 2 senses Webster, 1913

Treatise

/trēt'-əs/ · Trea·tise · IPA /ˈtɹiːtɪs/
01 n. A written composition on a particular subject, in which its principles are discussed or explained; a tract.
  1. 1.
    A written composition on a particular subject, in which its principles are discussed or explained; a tract.
    “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.
  2. 2.
    Story; discourse.[R.]