What Is the Plural of Hypothesis? Meaning, Rules, and Examples

Language learners and professionals alike often stumble upon the question: what is the plural of hypothesis? This is not only a matter of spelling but also of understanding how certain words of Greek origin function in English.

To make this simple, useful, and thorough, let us walk step by step through the grammar, history, usage, and practical applications of this word and its plural form. By the end, you will not only know the plural but also gain confidence in using it correctly in academic, scientific, and everyday contexts.

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What is the correct plural of hypothesis?

The plural of hypothesis is hypotheses. Instead of adding a regular “s” as in cats or tables, the ending shifts from -is to -es. This follows a well-established pattern for Greek words adopted into English.

• Singular: hypothesis

• Plural: hypotheses

This transformation comes from classical Greek rules where many words ending in -is form their plural with -es. The same applies to thesis (plural theses) and crisis (plural crises).

Why is the plural of hypothesis not hypotheses with “is” at the end?

The reason lies in etymology. Hypothesis comes from the Greek word hypóthesis, meaning “a foundation” or “a proposal.” When English borrowed the term through Latin, it kept much of the original structure.

According to historical linguistics studies at Oxford and Cambridge, English preserved many Greek plural endings because scholars wanted to maintain a link with classical texts. That is why today we still write hypotheses instead of a more regularized form such as hypothesises.

How do we use hypothesis and hypotheses in sentences?

Examples make the concept clearer. Consider these pairs that contrast singular and plural usage:

1. Singular: The scientist developed a new hypothesis about climate change.
   Plural: The scientists tested several hypotheses to explain the unusual weather patterns.

2. Singular: A hypothesis must be tested through observation and experiment.
   Plural: Competing hypotheses often arise in evolutionary biology.

3. Singular: She proposed a hypothesis linking diet to mental focus.
   Plural: Multiple hypotheses can be combined to form a broader theory.

4. Singular: A hypothesis is the first step in the scientific method.
   Plural: Different hypotheses can be eliminated when evidence contradicts them.

These examples show that hypothesis refers to one idea or assumption, while hypotheses refers to two or more.

What does hypothesis mean in simple terms?

A hypothesis is an educated guess or proposed explanation that can be tested. It is not just a random assumption but a statement that can be confirmed or disproven through evidence. In research, hypotheses are the bridge between questions and answers.

For example, if a doctor notices patients improve faster with more rest, the hypothesis might be: Rest speeds up recovery. Scientists then design experiments to test if that is true.

How are hypotheses important in education and research?

Universities emphasize hypotheses in both teaching and research. According to a 2023 study from the University of Michigan, students who practiced forming clear hypotheses showed better problem-solving skills across subjects.

In psychology, biology, economics, and even linguistics, hypotheses act as the foundation for experiments and theories. Without them, research would lack direction.

When students learn the plural hypotheses, they gain not only correct grammar but also an understanding of how science builds knowledge through multiple possible explanations.

Graphical guide to hypothesis vs. hypotheses

This table offers a quick reference to avoid confusion between the singular and plural.

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How does hypothesis differ from theory?

Many people confuse hypothesis and theory. A hypothesis is a starting point, often narrow in scope, while a theory is a well-developed explanation backed by extensive evidence.

• Hypothesis: Eating more fruits reduces fatigue.

• Theory: Germ theory of disease explains that microorganisms cause infections.

Notice that hypotheses become part of theories only when repeatedly tested and confirmed.

What other English words follow the same plural rule?

The plural form hypotheses belongs to a larger family of words. Knowing these helps reinforce the rule:

1. Thesis → Theses
   Example: Her thesis explored modern literature. Their theses covered many different subjects.

2. Crisis → Crises
   Example: The city faced a crisis. Several crises shaped its history.

3. Analysis → Analyses
   Example: One analysis proved the claim. Later, multiple analyses supported the conclusion.

4. Diagnosis → Diagnoses
   Example: The doctor gave a diagnosis. Other doctors gave alternative diagnoses.

These patterns confirm that hypothesis → hypotheses is not an exception but part of a consistent rule.

Why does this matter for learners of English?

Grammar is not only about correctness but also about clarity. Misusing singular and plural forms can confuse readers or listeners. Imagine a student writing: The researchers tested many hypothesis. This error signals a lack of mastery and might reduce credibility in academic or professional settings.

Research in applied linguistics from the University of Edinburgh in 2024 highlighted that learners who mastered irregular plurals had stronger performance in writing tasks, as evaluators perceived their work as more polished and trustworthy.

How to remember the plural of hypothesis?

Memory tricks can help:

• Think of thesis → theses. Since hypothesis contains thesis inside it, the plural follows the same path: hypothesis → hypotheses.

• Visualize the change: replace -is with -es.

• Practice with sentences: Write three sentences with hypothesis and three with hypotheses. Repetition builds habit.

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FAQ on the plural of hypothesis

Q1: What is the plural of hypothesis?
A1: The plural is hypotheses.

Q2: Can I say “hypothesises”?
A2: No. That form does not exist in standard English.

Q3: Is hypothesis always scientific?
A3: No. While often used in science, it can also describe assumptions in daily life. For instance, you might form a hypothesis about why a friend is late.

Q4: How do you pronounce hypotheses?
A4: It is pronounced hy-POTH-uh-seez. The final -es sounds like “eez.”

Q5: What is the difference between hypothesis and assumption?
A5: An assumption may not be testable, while a hypothesis must be testable and falsifiable.

Q6: Can hypotheses be wrong?
A6: Yes, and that is normal. In fact, disproving a hypothesis often leads to new discoveries.

Q7: Do all words ending in -is become -es in plural?
A7: Many do, especially those from Greek, but not all. Always check reliable dictionaries.

Q8: How do I teach students the plural of hypothesis?
A8: Use examples, repetition, and comparison with other words like thesis and analysis. Visual aids such as tables help reinforce the pattern.

Q9: Is there a difference in American and British English for this plural?
A9: No. Both use hypotheses.

Q10: Can I use “hypotheses” in non-academic writing?
A10: Yes. It is appropriate anywhere you need to describe multiple tentative explanations.

Conclusion

The plural of hypothesis is hypotheses, a form rooted in Greek grammar but firmly established in modern English. Understanding and using it correctly strengthens clarity in both academic and everyday contexts.

The rule is consistent with other words like thesis → theses and analysis → analyses. By practicing examples, using memory tricks, and appreciating its role in research and communication, learners can avoid mistakes and express themselves with greater precision.

Mastering such details may seem small, but they build the foundation of confident writing and speech. Just as a single hypothesis can lead to new knowledge, knowing how to handle hypotheses correctly opens the door to more accurate and professional communication.