thesis

noun

the·​sis ˈthē-səs 

British especially for sense 3 ˈthe-sis

plural theses ˈthē-ˌsēz 

1

: a dissertation embodying results of original research and especially substantiating a specific view

especially : one written by a candidate for an academic degree

2

a

: a proposition to be proved or one advanced without proof : hypothesis

b

: a position or proposition that a person (such as a candidate for scholastic honors) advances and offers to maintain by argument

3

a(1)

: the unstressed part of a poetic foot especially in accentual verse

(2)

: the longer part of a poetic foot especially in quantitative verse

b

: the accented part of a musical measure : downbeat compare arsis

4

: the first and least adequate stage of dialectic compare synthesis

Did you know?

In high school, college, or graduate school, students often have to write a thesis on a topic in their major field of study. In many fields, a final thesis is the biggest challenge involved in getting a master's degree, and the same is true for students studying for a Ph.D. (a Ph.D. thesis is often called a dissertation). But a thesis may also be an idea; so in the course of the paper the student may put forth several theses (notice the plural form) and attempt to prove them.

Synonyms of thesis

• argument
• contention
• assertion
• hypothesis
• theory

Examples of thesis in a Sentence

She wrote her thesis on Renaissance Nativity scenes.

a master's thesis on the effects of global warming

New evidence supports his thesis.

We disagreed with the basic thesis of the report.

The book's central thesis is that propaganda influences the masses in important ways.

Recent Examples on the Web

This earnings season, investors are starting to show signs of apprehension about AI’s investment thesis, putting pressure on some of the largest tech companies that have spent big to win the AI war. —John Kell, Fortune, 4 Feb. 2026

By correlating this economic power with global viewership trends, NNAF will validate the thesis that African content is not just culturally significant, but a commercially viable sector ready for institutional scale. —Melanie Goodfellow, Deadline, 4 Feb. 2026

This was my final test — my thesis of combining all my skills. —Ryan Gajewski, HollywoodReporter, 4 Feb. 2026

But what struck me in Davos this month was how AI's capital intensity has turned this from utility talking points into a genuine investment thesis with animal spirits behind it. —Justin Worland, Time, 30 Jan. 2026

Word History

Etymology

in sense 3, Middle English, lowering of the voice, from Late Latin & Greek; Late Latin, from Greek, downbeat, more important part of a foot, literally, act of laying down; in other senses, Latin, from Greek, literally, act of laying down, from tithenai to put, lay down — more at do

First Known Use

14th century, in the meaning defined at sense 3a(1)

Rhymes for thesis

• rhesus
• amniocentesis
• spondylolisthesis
• cytokinesis
• paracentesis
• plasmapheresis
• enuresis
• pollicis

Kids Definition

thesis

noun

the·​sis ˈthē-səs 

plural theses ˈthē-ˌsēz 

1

: a statement put forth for discussion or proof : hypothesis

2

: a long essay presenting the results of original research