1. a formal and systematic exposition in writing of the principles of a subject, generally longer and more detailed than an essay.

Origin of treatise

1300–50; Middle English tretis < Anglo-French tretiz, akin to Old French traitier to treat Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for treatises

Historical Examples of treatises

  • And have you not also met with the treatises of philosophers who say that like must love like?



  • Read on this subject the learned reply of Father Balthus to the treatises of MM.

    The Phantom World

    Augustin Calmet

  • Altogether there are some dozen treatises from these three men on chemical subjects.

  • Altogether he wrote some eighteen treatises on chemical subjects.

  • Then there were treatises on grammar, on orthography, and a series of works on mathematics.

British Dictionary definitions for treatises


  1. a formal work on a subject, esp one that deals systematically with its principles and conclusions
  2. an obsolete word for narrative

Word Origin for treatise

C14: from Anglo-French tretiz, from Old French tretier to treat
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for treatises



c.1300, from Anglo-French tretiz (mid-13c.), contracted from Old French traiteiz, from Gallo-Romance *tractaticius, from Latin tractare "to deal with" (see treat).

Online Etymology Dictionary, © 2010 Douglas Harper