[ thee-sis ]
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noun,plural the·ses [thee-seez]. /ˈθi siz/.
  1. a proposition stated or put forward for consideration, especially one to be discussed and proved or to be maintained against objections: He vigorously defended his thesis on the causes of war.

  2. a subject for a composition or essay.

  1. a dissertation on a particular subject in which one has done original research, as one presented by a candidate for a diploma or degree.

  2. Music. the downward stroke in conducting; downbeat.: Compare arsis (def. 1).

  3. Prosody.

    • a part of a metrical foot that does not bear the ictus or stress.

    • (less commonly) the part of a metrical foot that bears the ictus.: Compare arsis (def. 2).

  4. Philosophy. See under Hegelian dialectic.

Origin of thesis

First recorded in 1350–1400; Middle English, from Latin, from Greek thésis “a setting down, something set down,” equivalent to the- (stem of tithénai “to put, set down”) + -sis noun suffix; see -sis

word story For thesis

Thesis comes via Latin thesis from Greek thésis. There are only two meanings of thesis in Latin: in rhetoric, a general or abstract question (as opposed to a particular case), a proposition (the pure Latin term is propositum “something put forward”); and in poetry, the unstressed part of a metrical foot. However, Greek thésis has the opposite sense, the stressed part of a metrical foot. The Greek commentators explained thésis as the downward step of the foot (as of a marching soldier) or the lowering of the hand (as of a conductor indicating the accented beat). In Late Latin thesis meant “a lowering of the voice on an unstressed syllable” (its opposite is arsis, “a raising of the voice on a stressed syllable”). The sense “unstressed syllable or note” appears in English at the end of the 14th century and has been the accepted meaning since the 18th century in English poetry and music.
Thesis with the meaning “a proposition put forward to be discussed, proved, or defended” appeared in 1579; the more specific meaning “a dissertation required for an academic degree” dates from the second half of the 17th century. These meanings developed from the rhetorical sense in Latin and Greek.

Other words for thesis

Words that may be confused with thesis Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use thesis in a sentence

British Dictionary definitions for thesis


/ (ˈθiːsɪs) /

nounplural -ses (-siːz)
  1. a dissertation resulting from original research, esp when submitted by a candidate for a degree or diploma

  2. a doctrine maintained or promoted in argument

  1. a subject for a discussion or essay

  2. an unproved statement, esp one put forward as a premise in an argument

  3. music the downbeat of a bar, as indicated in conducting

  4. (in classical prosody) the syllable or part of a metrical foot not receiving the ictus: Compare arsis

  5. philosophy the first stage in the Hegelian dialectic, that is challenged by the antithesis

Origin of thesis

C16: via Late Latin from Greek: a placing, from tithenai to place

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

Cultural definitions for thesis


The central idea in a piece of writing, sometimes contained in a topic sentence.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.