hypothesis

American  

[hahy-poth-uh-sis, hi-] / haɪˈpɒθ ə sɪs, hɪ- /

noun

• hypotheses
  plural

1. 

   a proposition, or set of propositions, set forth as an explanation for the occurrence of some specified group of phenomena, either asserted merely as a provisional conjecture to guide investigation working hypothesis or accepted as highly probable in the light of established facts.

2. a proposition assumed as a premise in an argument.

3. the antecedent of a conditional proposition.

4. a mere assumption or guess.

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hypothesis British  

/ haɪˈpɒθɪsɪs /

noun

1. a suggested explanation for a group of facts or phenomena, either accepted as a basis for further verification ( working hypothesis ) or accepted as likely to be true Compare theory

2. an assumption used in an argument without its being endorsed; a supposition

3. an unproved theory; a conjecture

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hypothesis Scientific  

/ hī-pŏth′ĭ-sĭs /

• hypotheses
  plural

1. A statement that explains or makes generalizations about a set of facts or principles, usually forming a basis for possible experiments to confirm its viability.

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hypothesis Cultural  

1. plur. hypotheses (heye-poth-uh-seez) In science, a statement of a possible explanation for some natural phenomenon. A hypothesis is tested by drawing conclusions from it; if observation and experimentation show a conclusion to be false, the hypothesis must be false. (See scientific method and theory.)

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Usage

What is a hypothesis? In science, a hypothesis is a statement or proposition that attempts to explain phenomena or facts. Hypotheses are often tested to see if they are accurate. Crafting a useful hypothesis is one of the early steps in the scientific method, which is central to every field of scientific experimentation. A useful scientific hypothesis is based on current, accepted scientific knowledge and is testable. Outside of science, the word hypothesis is often used more loosely to mean a guess or prediction.

Synonym Usage

See theory.

Other Word Forms

Derived Forms

• counterhypothesis
  noun
• hypothesist
  noun
• subhypothesis
  noun

Inflected Forms

Nouns

• hypotheses
  plural

Etymology

Origin of hypothesis

First recorded in 1590–1600, hypothesis is from the Greek word hypóthesis “basis, supposition”; see hypo-, thesis

Explanation

In science, a hypothesis is an idea or explanation that you then test through study and experimentation. Outside science, a theory or guess can also be called a hypothesis. A hypothesis is something more than a wild guess but less than a well-established theory. In science, a hypothesis needs to go through a lot of testing before it gets labeled a theory. In the non-scientific world, the word is used a lot more loosely. A detective might have a hypothesis about a crime, and a mother might have a hypothesis about who spilled juice on the rug. Anyone who uses the word hypothesis is making a guess.

Example Sentences

See Examples For:

hypothesis hypotheses

They found that 20% of households lived “hand to mouth,” but that the consumption behavior of the other 80% was consistent with their forward-looking hypothesis.

From The Wall Street Journal ● Oct. 12, 2026

We’ve based our hypothesis on research and by examining how countries have dealt with disasters in recent years.

From Science Daily ● Sep. 22, 2026

I've got a hypothesis that people are becoming increasingly skeptical of written information.

From The Wall Street Journal ● Sep. 12, 2026

One hypothesis has proposed that Neornithes survived because many lived around aquatic environments, where conditions may have offered some protection from the devastation following the asteroid impact.

From Science Daily ● Sep. 11, 2026

Science is generated by and devoted to free inquiry: the idea that any hypothesis, no matter how strange, deserves to be considered on its merits.

From "Cosmos" by Carl Sagan

They use it to brainstorm ideas, find literature, improve writing, refine arguments and test competing hypotheses.

From The Wall Street Journal ● Sep. 28, 2026

China’s biotech hubs also have a dense network of specialized contract research organizations, or CROs—which are critical for running clinical tests—allowing researchers to quickly transform scientific hypotheses into results.

From The Wall Street Journal ● Sep. 11, 2026

To explain this contrast, the authors compare several hypotheses: natural selection, sex-biased demographic processes or partner preference.

From Science Daily ● Jul. 7, 2026

The continuing delay, he argues, points to competing hypotheses, unresolved leads and possible mechanical issues that have yet to be fully explained.

From BBC ● Jun. 15, 2026

From 1644 on, the use and status of hypotheses became a central issue.

From "The Invention of Science" by David Wootton

Related Words

• assumption
• axiom
• conclusion
• conjecture
• explanation
• guess
• inference
• interpretation
• premise
• proposition
• rationale
• supposition
• theorem
• thesis