Thesis vs. Theses – Which is Correct?

Thesis and theses are both correct English words, representing the singular and plural forms, respectively, of a fundamental academic concept. A thesis is a single statement or theory put forward as a premise to be maintained or proved, while theses refers to multiple such statements or theories.

Thesis or Theses – Which is Correct?

Both “thesis” and “theses” are grammatically correct words in American English, but they differ in number. Thesis is the singular form, referring to one central argument, proposition, or a substantial academic paper, such as a master’s thesis. Theses is the irregular plural form, used when referring to more than one such argument, proposition, or academic paper. The core distinction lies solely in whether you are discussing one item or multiple items.

The Best Trick to Remember the Difference

The easiest way to remember the difference is to focus on the ending. Thesis ends with ‘-is’, which sounds like “is singular.” Theses ends with ‘-es’, just like many other plural words (e.g., “boxes,” “classes”), indicating multiple items. Think of the extra ‘s’ sound in ‘theses’ as signifying “more than one.”

Word	Part of Speech	Meaning	Example
Thesis	Noun (singular)	A statement or theory put forward as a premise to be maintained or proved; a long essay or dissertation involving personal research, written by a candidate for a university degree.	Her thesis argued for significant reform in environmental policy.
Theses	Noun (plural)	Multiple statements, theories, or academic dissertations.	The library houses hundreds of graduate theses from various departments.

How to Use Thesis

The word “thesis” is used when referring to a single, central idea, argument, or a major academic paper. It’s a formal term often found in academic, scientific, or philosophical contexts. When you’re presenting one main point or discussing a solitary dissertation, “thesis” is the appropriate choice. It carries a sense of weight and intellectual rigor.

Example 1: The student spent two years researching and writing her doctoral thesis on renewable energy sources.

Example 2: His central thesis was that economic inequality leads to social unrest.

Example 3: The professor challenged the class to develop a strong, defensible thesis for their essays.

What are the different forms of Thesis?

“Thesis” is a noun that originates from Greek, and like many words of Greek origin ending in “-is” (e.g., crisis, analysis), it forms its plural by changing the “-is” to “-es.” Therefore, the plural form of “thesis” is “theses.” There are no other common grammatical forms (e.g., verb, adjective, adverb) derived directly from “thesis.”

Etymology of the word Thesis

The word “thesis” comes from the Greek word thésis, meaning “a placing, a proposition.” It is derived from the verb tithenai, which means “to place, to set.” In ancient Greek rhetoric, a thesis was a proposition or statement maintained by argument. This meaning evolved into the academic sense of a formal dissertation presented for a degree.

How to Use Theses

“Theses” is the plural form of “thesis,” meaning it should be used when you are referring to two or more central arguments, propositions, or academic dissertations. It maintains the formal tone of its singular counterpart and is predominantly used in academic, research, or intellectual discussions where multiple distinct arguments or papers are being considered collectively.

Example 1: The university’s digital archive contains thousands of master’s and Ph.D. theses.

Example 2: She compared the underlying theses of several prominent philosophical texts.

Example 3: The conference featured presentations on groundbreaking research and innovative theses from young scientists.

What are the different forms of Theses?

“Theses” is already the plural form of the noun “thesis.” It does not have further grammatical forms like verb tenses or degrees of comparison, as it is a fixed plural noun. Its singular form is “thesis.”

Etymology of the word Theses

As the plural form of “thesis,” “theses” shares the same etymological roots. It derives from the Greek word thésis, meaning “a placing, a proposition,” and ultimately from the verb tithenai, “to place, to set.” The pluralization follows the Greek grammatical pattern for words ending in “-is.”

Related Concepts

Understanding the broader grammatical concepts of singular and plural nouns, especially those with irregular forms, is key to correctly distinguishing between words like “thesis” and “theses.”

• Nouns: Words that represent a person, place, thing, or idea. “Thesis” is an abstract noun representing an idea or a document.
• Irregular Plural Nouns: Nouns that do not form their plural by simply adding “-s” or “-es.” Many words derived from Greek or Latin, like “thesis” (plural “theses”), “crisis” (plural “crises”), and “phenomenon” (plural “phenomena”), follow irregular pluralization rules.

Examples from Media and Literature

• “The author’s central thesis, that technology is inherently dehumanizing, permeated every chapter of the book.” (Literary Criticism)
• “In his acceptance speech, he outlined several key theses on the future of global cooperation.” (News Report)
• “The department requires all graduate students to submit their final thesis by the end of spring semester.” (University Handbook)
• “The symposium will feature a panel discussion where scholars will debate various theses on post-modern art.” (Academic Event Announcement)
• “Her groundbreaking thesis challenged conventional wisdom and opened new avenues for research.” (Biographical Account)

Practice Exercises

Choose the correct word to complete the sentence.

1. The professor asked each student to state their primary ______ for the debate.
2. The library acquired several new ______ on quantum physics this month.
3. Developing a strong ______ is the first step in writing a compelling essay.
4. During the conference, many scholars presented their innovative ______ on climate change.
5. She successfully defended her ______ and earned her doctorate.

Answer Key

1. thesis
2. theses
3. thesis
4. theses
5. thesis

Thesis Synonyms

Synonym	Definition
Argument	A reason or set of reasons given with the aim of persuading others that an action or idea is right or wrong.
Proposition	A statement or assertion that expresses a judgment or opinion.
Premise	A previous statement or proposition from which another is inferred or follows as a conclusion.
Hypothesis	A proposed explanation made on the basis of limited evidence as a starting point for further investigation.
Stance	The attitude or position of an individual or group toward something.

Theses Synonyms

Synonym	Definition
Arguments	Multiple reasons or sets of reasons given with the aim of persuading others.
Propositions	Multiple statements or assertions that express judgments or opinions.
Premises	Multiple previous statements or propositions from which others are inferred.
Hypotheses	Multiple proposed explanations made on the basis of limited evidence.
Stances	Multiple attitudes or positions of individuals or groups toward something.

Frequently Asked Questions

Question 1: Is “thesis” only used for academic papers?
No, while “thesis” is very common in academia for dissertations and major research papers, it can also refer to a central argument, statement, or proposition in any context, such as a philosophical thesis, a political thesis, or the main point of an essay.

Question 2: How do I pluralize other words like “thesis” that end in “-is”?
Many English words of Greek origin that end in “-is” form their plural by changing “-is” to “-es.” Examples include “crisis” (crises), “analysis” (analyses), “emphasis” (emphases), and “parenthesis” (parentheses).

Question 3: Can “thesis” be used as a verb?
No, “thesis” is strictly a noun. There is no verb form “to thesis.” You would typically use verbs like “to propose,” “to argue,” “to present,” or “to write” in relation to a thesis.

Conclusion

Mastering the distinction between thesis and theses is straightforward once you remember that thesis is singular, referring to one central argument or academic paper, and theses is its plural form, indicating multiple such items. Both are correct and vital terms, especially in academic and intellectual discourse.

Pro Tip: Always double-check the number when using these words. Incorrectly using “thesis” for multiple items or “theses” for a single one can subtly undermine your credibility in formal writing.