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

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 current price implies better-than-expected Tesla performance beginning next decade, with the bull thesis focusing on the company’s robotaxi and human robot business.

From The Wall Street Journal • Apr. 7, 2026

Anyone who maintains that thesis with high conviction would likely favor gold mining stocks at current prices.

From Barron's • Apr. 2, 2026

“The stock’s dip is probably more panic and less thesis collapse. Until proven otherwise, Nvidia is still the leader, but the burden of proof has shifted,” said Bill Birmingham, managing director of REX Financial.

From Barron's • Apr. 1, 2026

Samuel Adams’s master’s thesis was “delivered in flawless Latin,” Alexander Hamilton copied Demosthenes into his commonplace book, and Thomas Jefferson modeled his oratory on the prose of Livy, Sallust, and Tacitus.

From "Words Like Loaded Pistols" by Sam Leith

Related Words

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