Synonyms of theory

theory

noun

ˈthē-ə-rē 

as in hypothesis

an idea that is the starting point for making a case or conducting an investigation

set out to prove her theory that people can't really taste any difference between colas, so they buy according to the product's image

Synonyms & Similar Words

• hypothesis
• thesis
• proposition
• premise
• assumption
• suggestion
• guess
• supposition
• theorem
• impression
• proposal
• inference
• hunch
• conjecture
• concept
• speculation
• generalization
• suspicion
• presumption
• notion
• presupposition
• premiss
• conception
• concession
• construct
• abstraction
• surmise
• feeling
• guesswork
• proffer
• inkling

Antonyms & Near Antonyms

• fact
• knowledge
• assurance
• certainty

Synonym Chooser

How does the noun theory differ from other similar words?

The words hypothesis and law are common synonyms of theory. While all three words mean "a formula derived by inference from scientific data that explains a principle operating in nature," theory implies a greater range of evidence and greater likelihood of truth.

the theory of evolution

When would hypothesis be a good substitute for theory?

Although the words hypothesis and theory have much in common, hypothesis implies insufficient evidence to provide more than a tentative explanation.

a hypothesis explaining the extinction of the dinosaurs

When might law be a better fit than theory?

The meanings of law and theory largely overlap; however, 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

Example Sentences

Recent Examples of theory

Midway through Together, the debut feature from Australian filmmaker Michael Shanks, a character trots out Plato’s theory of halves. —David Fear, Rolling Stone, 1 Aug. 2025

While there are differences between matter and antimatter in our best theory of fundamental quantum physics, the standard model, these differences are far too small to explain where all the antimatter has gone. —William Barter, Space.com, 1 Aug. 2025

Einstein’s theory of relativity states that gravity, a fundamental force of attraction, is the curvature of space-time itself. —Madison Dapcevich, Discover Magazine, 1 Aug. 2025

But Margulis took her theory further; in her view, symbiosis was the driving force of evolution, and many entities were likely composites. —Zoë Schlanger, The Atlantic, 23 July 2025