How to Use Thesis Plural (Explained, With Examples)

What’s the plural of “thesis”?

A thesis is “a long piece of writing on a particular subject, especially one that is done for a higher college or university degree.” The plural of thesis is theses (pronounced thee-seez).

👍🏼Usage Note

✓
She submitted her thesis on quantum mechanics.

✓
The professor supervised several theses this year.

✗
He wrote two thesis during his studies.

✗
The students presented their thesises at the conference.

Thesis is singular.
The plural of thesis is theses (thee-seez).

Nouns that end in –sis

Many Greek-origin nouns ending in -sis form their plural by replacing -is with -es. Examples include analysis → analyses, crisis → crises, oasis → oases, synopsis → synopses, and thesis → theses.

Noun: thesis	Example sentences
thesis	She defended her thesis on renewable energy last spring. The student's thesis argued for a new interpretation of the sources. A clear thesis statement helps structure the entire paper. His advisor helped refine the central thesis before submission.
theses (plural)	The department archive contains dozens of graduate theses. Several theses examined similar methodologies across disciplines. Evaluation committees reviewed the final theses this term.

Greek nouns in English

Thesis comes from Greek θέσις (thésis), meaning “a proposition, a setting down, position, thesis,” from the root τίθημι (títhēmi), “I put, place, set.”

How to Use Thesis Plural (Explained, With Examples)

What’s the plural of “thesis”?

Nouns that end in –sis

Synonyms, nearby words, and etymology

thesis

Exercise: Irregular, Greek plurals