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What’s the Plural of Hypothesis?

The plural of hypothesis is hypotheses. Hypothesis is the singular noun form.

The plural of “hypothesis”

  • The plural of hypothesis is hypotheses (sounds like hi-paw-thuh-seas).

  • Hypotheses is the only recognized plural of hypothesis.

What’s with the word hypothesis, and why does it behave the way it does from its singular to plural form? Keep reading.

The correct use of hypotheses (plural) in setences.

What’s the meaning of hypothesis?

Hypothesis comes from the Greek word of the same spelling, hypothesis, meaning, “base, groundwork, foundation”. Hypothesis is made up of the Greek root words, hypo + thesis: “hypo” meaning “under” or “placing under”; “thesis“, meaning “a placing, proposition”, (from Etymonline).

So, based on the noun’s construction, hypothesis means to put or set forward a thesis or proposal to be subject to further investigating. According to Wikipedia, hypotheses are:

Tentative conjectures explaining an observation, phenomenon or scientific problem that can be tested by further observation, investigation and/or experimentation.

Wikipedia on the word hypothesis.

Why is “hypotheses” plural for “hypothesis”?

"Hypothesis" (singular) in sentence examples.

Lots of people confuse the plural of hypothesis, and it’s not tough to see why: hypothesis is an irregular plural noun form that omits the -s/-es of regular plural nouns. Apart from this, the way hypothesis modifies from singular to plural effectively changes the spelling and pronunciation of the word by substituting the -sis as a singular to –ses plural.

Most nouns add an -s/-es to denote plural. Hypothesis, and similar sounding nouns such as crisis, thesis, oasis, nemesis, diagnosis, analysis and so on, all change to -ses in their plural forms.

Nouns that end in “sis”

Each of these irregular plural nouns have another thing in common: they’re all Greek words that use Greek suffixes.  So, in case you didn’t know, we all speak a bit of Greek.

Greek nouns in English

Examples of “hypothesis” (singular) in sentences

Other chemists rejected his hypothesis.

What we need is a general hypothesis to explain merger waves.

Their hypothesis is that watching excessive amounts of television reduces a person’s ability to concentrate.

The results of the experiment did not support his hypothesis.

She wrote something to summarize her hypothesis.

Examples of “hypotheses” (plural) in sentences

It will be evident that no direct record of this evolution can be expected, and recourse must be had to hypotheses founded on the indirect evidence available.

The hypotheses which carried it back to the early years of the Christian era have been wholly abandoned.

Various hypotheses have been put forward to explain this increase.

In the above work we have a combination of the redaction and sources hypotheses.

Such hypotheses attend to Aristotle’s philosophy to the neglect of his life.

Synonyms of “hypothesis”

  • assumption
  • supposition
  • proposition
  • guess
  • conjecture
  • explanation
  • premise
  • inference
  • conclusion
  • interpretation
  • thesis
  • theory
  • supposition
  • proposal

Read about other irregular plurals

Origin of “hypothesis”

From etymonline:

1590s, “a particular statement;” 1650s, “a proposition, assumed and taken for granted, used as a premise,” from French hypothese and directly from Late Latin hypothesis, from Greek hypothesis.


  1. Wikipedia hypothesis.
  2. Synonyms for hypothesis.
  3. Hypotheses sentence examples.
  4. Origin of hypothesis.

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