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

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

The "capture" hypothesis meanwhile postulates that the moons are asteroids from the outer Solar System that were captured by Mars' gravity.

From Barron's ● Aug. 16, 2026

For decades, mathematicians have tried to prove the Riemann hypothesis, which says that 100% of the nontrivial zeros of the Riemann zeta function fall on a single vertical line.

From The Wall Street Journal ● Aug. 15, 2026

But a rousing of the stellar fires in N49 is a simpler hypothesis: we are sure there are such things as supernovae.

From "Cosmos" by Carl Sagan

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

But there are several hypotheses, says Dr Alex Gofton, a tick expert who led a recent study into the allergy.

From BBC ● Jul. 20, 2026

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

From Los Angeles Times ● May 7, 2026

However, if scientists can use data from large cosmological surveys to develop precise hypotheses that apply to the solar system, then it becomes possible to design targeted experiments to test them.

From Science Daily ● Apr. 24, 2026

There are neural centers for generating, spontaneously, numberless hypotheses about the facts of life.

From "The Lives of a Cell" by Lewis Thomas

Related Words

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