thesis

American  

[thee-sis] / ˈθi sɪs /

noun

plural

theses

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.

   Synonyms:

   proposal, contention, theory

2. a subject for a composition or essay.

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

4. Music. the downward stroke in conducting; downbeat.

5. Prosody.

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

   2. (less commonly) the part of a metrical foot that bears the ictus.

6. Philosophy. Hegelian dialectic

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thesis British  

/ ˈθiːsɪs /

noun

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

3. a subject for a discussion or essay

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

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

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

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

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thesis Cultural  

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

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Usage

Plural word for thesis The plural form of thesis is theses, pronounced [ thee-seez ]. The plurals of several other singular words that end in -is are also formed in this way, including hypothesis/hypotheses, crisis/crises, and axis/axes. A similar change is made when pluralizing appendix as appendices. Irregular plurals that are formed like theses derive directly from their original pluralization in Latin and Greek.

Etymology

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; -sis

Explanation

A thesis is the most important or foundational idea of an argument. If the thesis of your paper is that chocolate ice cream is better than vanilla, you'll need to back that up with plenty of sundae-based research. The noun thesis has more than one important sense to it. One definition of thesis is that it is the most important or foundational idea of an argument, presentation, or piece of writing. But it can also mean a large work of art, criticism, or scientific research that represents original research and is generally the final requirement for an academic degree.

Example Sentences

That claim is more supportable than the thesis Mr. Scheiber draws from it, namely the college-educated working class is becoming a dynamic force for progressive social change.

From The Wall Street Journal • Apr. 12, 2026

In Boston’s view, it also adds to his thesis that a rearmament movement around the globe is likely only getting started.

From MarketWatch • Apr. 9, 2026

The stop is quite clear with any close below the 200-day simple moving average at $245 invalidates the bullish thesis.

From Barron's • Apr. 7, 2026

Public users start by typing in a strategy or investment thesis, then refine its parameters with follow-up questions.

From The Wall Street Journal • Apr. 3, 2026

With great relief, Helmuth finishes his final thesis, turns it in, and on the last day of school, Herr Meins stands in front of the class, grasping the graded papers.

From "The Boy Who Dared" by Susan Campbell Bartoletti

Related Words

• contention
• hypothesis
• opinion
• premise
• proposition
• supposition
• theory