thesis

American  

[thee-sis] / ˈθi sɪs /

noun

theses plural

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.

Other Word Forms

Noun Inflected Forms

• theses
  plural

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; see -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

See Examples For:

thesis theses

No, not unless I had a system whose outputs I’d already tested, and I’d want to see how credible its answers are and how much they change with a different thesis.

From MarketWatch ● Jul. 27, 2026

I first met the Westerinen family in 1999 as a graduate student in New York City, writing my thesis on the rise of genetic genealogy.

From Salon ● Jul. 27, 2026

Kurdi, who dedicated her doctoral thesis to the monastery complex, said they needed to "review old plans" to reinstall the base of the main column "and the part that remained of it".

From Barron's ● Jul. 20, 2026

"It is a tour de force of Yao Xue's PhD thesis work, pairing an innovative approach with exceptional electrophysiological skill."

From Science Daily ● Jul. 14, 2026

“Is he under a lot of stress? Working on his thesis or something?”

From "The Secret History" by Donna Tartt

Notice that many of theses names are software or consumer and business services companies.

From Barron's ● May 13, 2026

Everyone has their theses, and all are in search of the venue to share them.

From Slate ● Feb. 23, 2026

Ms. Beilock’s list of five ways American higher education can earn back public trust should be nailed to the door of every college president like Martin Luther’s 95 theses.

From The Wall Street Journal ● Feb. 4, 2026

Since its introduction, fifteen dissertations and final theses at Freie Universität have focused on the topic, along with seven additional dissertations completed by researchers in other countries.

From Science Daily ● Jan. 7, 2026

The literary theses required by French universities are, as a rule, volumes of several hundred pages, and more important in character even than the German Habilitationsschrift.

From Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 1 "Evangelical Church Conference" to "Fairbairn, Sir William" by Various

Related Words

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