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.

---

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

---

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.

---

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.)

---

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

Ryan Williams: I did not fully believe the hypothesis, and I'm on the record as a prominent skeptic.

From Barron's ● Oct. 30, 2026

If the models went from being stumped by long division to cracking the quasi-Riemann hypothesis in five years, how will the next five years play out?

From The Wall Street Journal ● Oct. 24, 2026

The adaptive aging hypothesis could also provide scientists with another way to examine the differences between normal cognitive aging and Alzheimer's disease.

From Science Daily ● Oct. 20, 2026

A new paper looking at the chemical reactions between water and disintegrating plastic offers a potential hypothesis for how microplastics might make us sick.

From Los Angeles Times ● Oct. 17, 2026

It is the same idea we associate with the name of Copernicus, whom Galileo described as the “restorer and confirmer,” not the inventor, of the heliocentric hypothesis.'

From "Cosmos" by Carl Sagan

"When we get the sample back, we'll be able to look in detail at its chemistry and its mineral composition - and the two hypotheses will produce very distinct results," said Sara Russell.

From BBC ● Oct. 18, 2026

It offers disciplined methods for testing hypotheses, challenging assumptions and correcting errors.

From The Wall Street Journal ● Sep. 13, 2026

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

Finally the new science was given a distinctive identity by a new language of facts, theories, hypotheses and laws.

From "The Invention of Science" by David Wootton

Random Word

Spin the wheel and learn a new word!

---

Related Words

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

---