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
• 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

One theory, according to Perreault, was that the Kingdom had been planning to burn the building down, Waco-style, if the government intervened. — Zander Sherman, Rolling Stone, 7 Aug. 2026

In a dueling report, House Democrats argued Fauci didn't play a role in drafting the paper and wasn't trying to silence other theories. — Joe Walsh, CBS News, 6 Aug. 2026

But supporters of the lab leak theory note that the analysis of the virus by scientists relied on incomplete data provided by the Chinese government. — Eric McDaniel, NPR, 6 Aug. 2026

The defense wrote that Lee’s statements in the recorded phone calls directly contradicted the defensive theory and strategy that Gonzalez was the person who caused all the injuries and the death of the child. — Shambhavi Rimal, Fort Worth Star-Telegram, 6 Aug. 2026