What’s the Plural of Thesis?

The English language is full of irregular plural forms that can catch even the most seasoned speakers off guard. One word that often causes confusion is “thesis.” Whether you’re writing a research paper, preparing for a presentation, or simply engaging in academic discussions, knowing the correct plural form of “thesis” is essential. In this article, we will explore the correct plural form of “thesis,” explain why it takes that form, provide examples of its usage in both singular and plural contexts, and answer common questions and misconceptions.

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What Does “Thesis” Mean?

Before we dive into pluralization, let’s start by understanding the meaning of “thesis.”

A thesis is a scholarly or academic document that presents the author’s research or findings on a particular subject. It is often written as a requirement for completing a degree, particularly at the master’s or doctoral level. In a broader sense, the word “thesis” can also refer to a central argument or statement that is being supported or proven in a piece of writing or speech.

Key Characteristics of a Thesis:

• Academic Research: A thesis typically involves original research, analysis, or argumentation on a specific topic.
• Degree Requirement: At universities, students are often required to submit a thesis to fulfill the requirements for a degree.
• Central Argument: A thesis can also mean the main idea or central argument that is being supported in an essay or research paper.

Examples of “Thesis” in Singular Form:

• She submitted her thesis on climate change to the university for review.
  (Here, “thesis” refers to one academic document.)
• The professor asked the students to summarize the thesis of the article.
  (In this sentence, “thesis” refers to the central argument of the article.)
• His doctoral thesis focused on the impact of artificial intelligence on job markets.
  (In this example, “thesis” is used to describe a single research project.)

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What’s the Plural of “Thesis”?

The plural of “thesis” is “theses.” Unlike many English nouns, which form their plural by simply adding “-s” or “-es” to the end, “thesis” follows a different pattern of pluralization. This is because “thesis” is derived from Greek, and many Greek-origin words in English have irregular plural forms.

Why “Theses” Instead of “Thesises”?

The word “thesis” comes from the Greek word “thesis,” which means “a proposition” or “a setting down.” In Greek, the plural of “thesis” is “theseis.” When the word was borrowed into Latin and later English, the plural form was adapted to “theses” to reflect its Greek origins.

This pattern is common among English words with Greek roots. Other examples include:

• Crisis → Crises
• Analysis → Analyses
• Hypothesis → Hypotheses

In all of these words, the “-is” ending is replaced with “-es” to form the plural. It’s important to note that the pronunciation also changes slightly when pluralized. While “thesis” is pronounced /ˈθiː.sɪs/, the plural “theses” is pronounced /ˈθiː.siːz/ (with a long “e” sound in the second syllable).

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Examples of “Theses” in Sentences

Now that we know the correct plural form of “thesis,” let’s look at some examples of “theses” in sentences to help clarify its usage.

Everyday Usage:

• The library has a collection of theses submitted by graduate students over the last 50 years.
  (Here, “theses” refers to multiple academic documents written by students.)
• Several theses on renewable energy have been published in the university’s journal.
  (In this sentence, “theses” refers to more than one research paper on the same topic.)
• The committee reviewed all the theses before deciding on the award for best research.
  (Here, “theses” refers to multiple theses being evaluated by a committee.)

In Academic Contexts:

• The university requires students to submit their theses electronically before graduation.
  (In this context, “theses” refers to the academic documents of multiple students.)
• Many students struggle with organizing their theses and presenting their arguments clearly.
  (Here, “theses” refers to the written documents of multiple students.)
• The professor has supervised over 50 theses during her career.
  (This sentence refers to the many theses that the professor has guided.)

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Singular vs. Plural: “Thesis” vs. “Theses”

As with most nouns, “thesis” has both a singular and plural form. “Thesis” refers to one research paper or central argument, while “theses” refers to more than one. Let’s clarify this distinction with a few examples:

Singular (“Thesis”) in Sentences:

• Her master’s thesis was well-researched and received high praise from the faculty.
  (Here, “thesis” refers to one particular research document.)
• The thesis of the essay is that economic inequality is the root cause of social unrest.
  (In this sentence, “thesis” refers to the main argument of the essay.)
• He defended his thesis on the philosophy of language in front of a panel of experts.
  (Here, “thesis” refers to one academic project.)

Plural (“Theses”) in Sentences:

• The university’s library contains hundreds of doctoral theses on a wide range of topics.
  (Here, “theses” refers to multiple academic documents housed in the library.)
• The students presented their theses at the conference, each showcasing their original research.
  (In this sentence, “theses” refers to the work of multiple students.)
• The academic journal publishes the best theses submitted by students each year.
  (Here, “theses” refers to more than one paper selected for publication.)

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Why Do Some People Confuse the Plural of “Thesis”?

The confusion around the plural of “thesis” likely arises from the fact that most English nouns form their plurals by simply adding “-s” or “-es.” Because “thesis” is of Greek origin and follows an irregular pluralization pattern, people might mistakenly think that “thesises” is the correct plural form. However, as we’ve seen, “theses” is the correct pluralization.

Common Mistakes

Mistake 1: Using “Thesises”
Some people incorrectly add “-es” to “thesis” to form the plural “thesises.” This is incorrect. The proper plural form is “theses.”

Incorrect:

• The students submitted their thesises to the committee for approval.

Correct:

• The students submitted their theses to the committee for approval.

Mistake 2: Confusing “Thesis” and “Theses”
Another common mistake is using “thesis” when referring to multiple theses, or using “theses” when referring to just one.

Incorrect:

• He wrote several thesis during his academic career.
  (When referring to more than one thesis, use “theses”.)

Correct:

• He wrote several theses during his academic career.

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How to Use “Theses” Correctly in Sentences

Whether you’re working on your own thesis, reviewing others’ work, or discussing academic research, knowing how to use “theses” correctly is important. Let’s look at some specific contexts where the plural form is used.

In Academic Writing:

• The university requires all students to submit their theses in both digital and print formats.
  (Here, “theses” refers to the academic documents of multiple students.)
• The journal published the best theses submitted in the field of environmental science.
  (In this sentence, “theses” refers to the work of several students on a specific subject.)
• The professor has supervised dozens of theses on various topics in philosophy.
  (Here, “theses” refers to the many research projects guided by one professor.)

In Conferences and Presentations:

• At the conference, graduate students presented their theses to an audience of peers and professors.
  (In this context, “theses” refers to the academic work of multiple students.)
• The panel reviewed the theses and selected the top three for awards.
  (Here, “theses” refers to multiple research documents submitted for evaluation.)
• Researchers from around the world shared their theses on global economic trends.
  (This sentence refers to the research papers presented by different researchers.)

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Common Questions and Misconceptions About “Theses”

Let’s address some common questions and misconceptions about the plural form of “thesis.”

Question 1:

Is “thesises” ever correct?

Answer:
No, “thesises” is never correct. The proper plural form is “theses.”

Example:

• The students submitted their theses on time for graduation.

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Question 2:

Why isn’t the plural of “thesis” just “thesises”?

Answer:
The word “thesis” comes from Greek, and many words of Greek origin have irregular plural forms in English. For words like “thesis,” the “-is” changes to “-es” in the plural, forming “theses.”

Example:

• The professor has reviewed several brilliant theses this year.

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Question 3:

Which plural form should I use in formal writing: “theses” or “thesises”?

Answer:
Always use “theses” in formal writing. “Thesises” is incorrect and should be avoided.

Example (Correct for formal writing):

• The theses were published in the university’s research journal.

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Question 4:

Which sentence is correct?

a) The students submitted their thesises to the faculty for approval.
b) The students submitted their theses to the faculty for approval.

Answer:
*b) The students submitted their theses to the faculty for approval.

Explanation: The correct plural form of “thesis” is “theses.” “Thesises” is incorrect.

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Practice Questions: Thesis or Theses?

Let’s test your understanding of when to use “thesis” and when to use “theses” with some practice questions.

Question 1:

Which word is correct in the following sentence?

• The professor has supervised several brilliant _ this year.

a) thesis
b) theses

Answer:
b) theses

Explanation: Since the sentence refers to more than one thesis, the correct plural form is “theses.”

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Question 2:

Fill in the blank with the correct word:

• She spent three years working on her _ for her master’s degree.

Answer:
Thesis

Explanation: The sentence refers to a single research paper, so “thesis” is the correct singular form.

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Question 3:

True or False:
“Thesises” is an acceptable plural form of “thesis.”

Answer:
False

Explanation: The correct plural form is “theses.” “Thesises” is incorrect.

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Question 4:

Which sentence is correct?

a) The researcher wrote multiple thesis on the same subject.
b) The researcher wrote multiple theses on the same subject.

Answer:
*b) The researcher wrote multiple theses on the same subject.

Explanation: The correct plural form of “thesis” is “theses.”

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Conclusion

In summary, the plural form of “thesis” is “theses.” This follows the irregular pluralization pattern found in many Greek-origin words. Knowing and using the correct plural form is important in both academic and formal contexts.

Key Takeaways:

• “Thesis” is singular, referring to one research paper or central argument.
• “Theses” is the correct plural form and should always be used when referring to more than one.
• Avoid using “thesises,” as it is incorrect.

By mastering the correct plural form of “thesis,” you can confidently use “theses” in a variety of contexts, whether you’re writing an academic paper, discussing research, or presenting at a conference.