/ Dictionary / Index T treatise: Meaning and Definition of Find definitions for: trea•tise Pronunciation: (trē'tis), [key] — n. a formal and systematic exposition in writing of the principles of a subject, generally longer and more detailed than an essay. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: treatise (Thesaurus) treatable treatment Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language