hypothesis

American  

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

noun

plural

hypotheses

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 /

plural

hypotheses

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.

Related Words

See theory.

Other Word Forms

• counterhypothesis noun
• hypothesist noun
• subhypothesis noun

Etymology

Origin of hypothesis

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

That’s the hypothesis of one of the world’s shrewdest and most respected analysts of geopolitics and energy, Cambridge University political economy professor Helen Thompson.

From MarketWatch • Apr. 11, 2026

Subject lines include “Recognizing the need for fasting,” “Mice blood age affects Alzheimer’s brain changes,” and “A casual hypothesis about epigenetics.”

From Slate • Mar. 30, 2026

The biggest flaw in the Hegelian viewpoint about supposedly great men is that his entire hypothesis about an unfolding historical process is flat wrong.

From Salon • Mar. 28, 2026

"We're able to test this hypothesis for the first time in a legitimate way," Barnes said.

From Science Daily • Feb. 23, 2026

The clay hypothesis hardly excludes life on Mars, but it certainly carries us far enough to say that there is no compelling evidence for microbiology on Mars.

From "Cosmos" by Carl Sagan

Related Words

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