hypothesis

noun
hy·​poth·​e·​sis | \ hī-ˈpä-thə-səs How to pronounce hypothesis (audio) \
plural hypotheses\ hī-​ˈpä-​thə-​ˌsēz How to pronounce hypotheses (audio) \

Definition of hypothesis

1a : an assumption or concession made for the sake of argument
b : an interpretation of a practical situation or condition taken as the ground for action
2 : a tentative assumption made in order to draw out and test its logical or empirical consequences
3 : the antecedent clause of a conditional statement

Keep scrolling for more

Choose the Right Synonym for hypothesis

hypothesis, theory, law mean a formula derived by inference from scientific data that explains a principle operating in nature. hypothesis implies insufficient evidence to provide more than a tentative explanation. a hypothesis explaining the extinction of the dinosaurs theory implies a greater range of evidence and greater likelihood of truth. the theory of evolution law implies a statement of order and relation in nature that has been found to be invariable under the same conditions. the law of gravitation

The Difference Between Hypothesis and Theory

A hypothesis is an assumption, an idea that is proposed for the sake of argument so that it can be tested to see if it might be true.

In the scientific method, the hypothesis is constructed before any applicable research has been done, apart from a basic background review. You ask a question, read up on what has been studied before, and then form a hypothesis.

A hypothesis is usually tentative; it's an assumption or suggestion made strictly for the objective of being tested.

A theory, in contrast, is a principle that has been formed as an attempt to explain things that have already been substantiated by data. It is used in the names of a number of principles accepted in the scientific community, such as the Big Bang Theory. Because of the rigors of experimentation and control, it is understood to be more likely to be true than a hypothesis is.

In non-scientific use, however, hypothesis and theory are often used interchangeably to mean simply an idea, speculation, or hunch, with theory being the more common choice.

Since this casual use does away with the distinctions upheld by the scientific community, hypothesis and theory are prone to being wrongly interpreted even when they are encountered in scientific contexts—or at least, contexts that allude to scientific study without making the critical distinction that scientists employ when weighing hypotheses and theories.

The most common occurrence is when theory is interpreted—and sometimes even gleefully seized upon—to mean something having less truth value than other scientific principles. (The word law applies to principles so firmly established that they are almost never questioned, such as the law of gravity.)

This mistake is one of projection: since we use theory in general to mean something lightly speculated, then it's implied that scientists must be talking about the same level of uncertainty when they use theory to refer to their well-tested and reasoned principles.

The distinction has come to the forefront particularly on occasions when the content of science curricula in schools has been challenged—notably, when a school board in Georgia put stickers on textbooks stating that evolution was "a theory, not a fact, regarding the origin of living things." As Kenneth R. Miller, a cell biologist at Brown University, has said, a theory "doesn’t mean a hunch or a guess. A theory is a system of explanations that ties together a whole bunch of facts. It not only explains those facts, but predicts what you ought to find from other observations and experiments.”

While theories are never completely infallible, they form the basis of scientific reasoning because, as Miller said "to the best of our ability, we’ve tested them, and they’ve held up."

Examples of hypothesis in a Sentence

In contrast to Bingham's hypothesis that Machu Picchu was the birthplace of the first Inca and the hearth area of the Inca civilization, current scholars believe that the city was built as a country estate … — Roger Balm, Focus On Geography, Spring 2004 Campus veterans marvel at all the poolside apartments that have sprung up since Georgia popped the income cap off its merit awards. Professors are testing their hypothesis that instead of increasing college enrollment, the state's $1.7 billion scholarship program has been a blessing for the automobile industry—since so many families roll the savings into buying new cars. — Greg Winter, New York Times, 31 Oct. 2002 Isaac Newton initially argued against a parabolic orbit for the … comet of 1680, preferring the hypothesis of two independent comets, one for the inbound and one for the outbound leg. However, Newton later showed that the orbit of the comet could indeed be fit by a parabola. — Daniel C. Boice and Walter Huebner, "Physics and Chemistry of Comets," in Encyclopedia of the Solar System Paul R. Weissman et al., editors1999 As stated, our working hypothesis suggests a straightforward way to look for evidence that would confirm or disconfirm it: can you predict what is omitted and what is included in alphabetic representations? — Timothy Shopen and Joseph M. Williams, Standards and Dialects in English, 1980 Other chemists rejected his hypothesis. Their hypothesis is that watching excessive amounts of television reduces a person's ability to concentrate. The results of the experiment did not support his hypothesis.
See More
Recent Examples on the Web Zimov and his colleagues have released large herbivores like bison into a nature preserve in Yakutia over the last few years to test the hypothesis. Kiona N. Smith, Ars Technica, "Beautifully preserved cave bears emerge from Siberian permafrost," 14 Sep. 2020 The Duke researchers’ hypothesis for why the gaiter seemed worse than no mask at all was that the fabric was splitting larger droplets into smaller aerosols. Joe Lindsey, Outside Online, "What You Need to Know About Wearing a Face Mask Outside," 30 Sep. 2020 In an analysis in the same issue of Science, another researcher, Suzana Herculano-Houzel of Vanderbilt University, makes a critique of the study’s hypothesis. Caroline Delbert, Popular Mechanics, "Crows Are Self-Aware and 'Know What They Know,' Just Like Humans," 28 Sep. 2020 The idea put forth in the study by Siraj and Loeb is known as panspermia, the hypothesis that life on one planet originated from microorganisms in outer space and moved to another. Chris Ciaccia, Fox News, "Meteors that brushed Earth's atmosphere may have brought life to Venus, study says," 27 Sep. 2020 But his new work lends credibility to Karten’s original hypothesis. Bret Stetka, Scientific American, "Bird Brains Are Far More Humanlike Than Once Thought," 24 Sep. 2020 Within weeks of the first gravitational wave announcement from LIGO in 2016, the primordial black hole hypothesis roared back to life. Quanta Magazine, "Physicists Argue That Black Holes From the Big Bang Could Be the Dark Matter," 23 Sep. 2020 The research team, including scientists from the University of Chicago, tested their hypothesis by simulating how the interiors of carbon-rich exoplanets could create diamonds through high levels of heat and pressure. Ashley Strickland, CNN, "Carbon-rich planets made of diamonds may exist beyond our solar system, study says," 14 Sep. 2020 Recent evidence undermines the hypothesis that the novel coronavirus originated in Huanan, but demands for the elimination of wet markets have continued to spread. Sam Sontag, TheWeek, "Wet markets are essential to Thai cooking. So why are they disappearing?," 20 Sep. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'hypothesis.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of hypothesis

1641, in the meaning defined at sense 1a

History and Etymology for hypothesis

Greek, from hypotithenai to put under, suppose, from hypo- + tithenai to put — more at do

Keep scrolling for more

Learn More about hypothesis

Time Traveler for hypothesis

Time Traveler

The first known use of hypothesis was in 1641

See more words from the same year

Statistics for hypothesis

Last Updated

20 Oct 2020

Cite this Entry

“Hypothesis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hypothesis. Accessed 30 Oct. 2020.

Keep scrolling for more

More Definitions for hypothesis

hypothesis

noun
How to pronounce hypothesis (audio)

English Language Learners Definition of hypothesis

: an idea or theory that is not proven but that leads to further study or discussion

hypothesis

noun
hy·​poth·​e·​sis | \ hī-ˈpä-thə-səs How to pronounce hypothesis (audio) \
plural hypotheses\ -​ə-​ˌsēz \

Kids Definition of hypothesis

: something not proved but assumed to be true for purposes of argument or further study or investigation

hypothesis

noun
hy·​poth·​e·​sis | \ hī-ˈpäth-ə-səs How to pronounce hypothesis (audio) \
plural hypotheses\ -​ˌsēz How to pronounce hypotheses (audio) \

Medical Definition of hypothesis

: a proposition tentatively assumed in order to draw out its logical or empirical consequences and test its consistency with facts that are known or may be determined it appears, then, to be a condition of the most genuinely scientific hypothesis that it be…of such a nature as to be either proved or disproved by comparison with observed facts— J. S. Mill

Keep scrolling for more

Comments on hypothesis

What made you want to look up hypothesis? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

Test Your Vocabulary

Here Be Dragons: A Creature Identification Quiz

  • monster werewolf photo
  • Which is a synonym of werewolf?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Syn City

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!