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

Years earlier, Leonardo had performed his own study of proportions, based on the theories of the ancient Roman architect Vitruvius. —Steven Strogatz, New York Times, 16 June 2025

Hit PLAY on the video above to watch TVLine’s full interview with Henrie and Brown, which includes more teases about what’s still to come, then drop a comment with your own thoughts about Wizards Beyond Waverly Place Season 2 — including your wildest theories. —Andy Swift, TVLine, 15 June 2025

Naidu also said the government will look at all possible theories of what led to the crash. —Reuters, CNN Money, 14 June 2025

Elijah walked beyond the Royalton premises to the property of the Sunset Royal Beach Hotel, according to the theory of the lawyers who represent the corporation that operates the Royalton. —Emerson Clarridge, Fort Worth Star-Telegram, 13 June 2025