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

By April, it had the data to support its hypothesis.

From The Wall Street Journal ● Aug. 28, 2026

A Sussex Police spokesperson said the investigation remained open, and the "current hypothesis" was that it was "a tragic accident, with no third-party involvement".

From BBC ● Aug. 22, 2026

Their hypothesis was confirmed when footage of a Ying Yang Twins performance went viral in 2025.

From Los Angeles Times ● Aug. 21, 2026

One theory for the origin of the Martian moons -- the "giant impact" hypothesis -- is that they formed after a celestial body collided with Mars.

From Barron's ● Aug. 16, 2026

But this twist effectively marks the birth of a new philosophy of science: a scientific principle is now an hypothesis that has survived the test of experience.

From "The Invention of Science" by David Wootton

Some medical researchers let AI models take the lead alongside human lab workers to gather information, stress-test hypotheses, interpret data and spit out plans.

From The Wall Street Journal ● Jul. 26, 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

It also puts forward hypotheses about why this belly-brain choreography exists.

From Los Angeles Times ● May 7, 2026

As he had done at Renault, de Meo distilled his hypotheses into a short memo, circulated to senior managers on his first day.

From The Wall Street Journal ● Apr. 9, 2026

As far as Newton was concerned the only worthwhile hypotheses were the ones that could be tested: and if they survived testing they ceased to be hypotheses.

From "The Invention of Science" by David Wootton

Related Words

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