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

The theory that Epstein was blackmailing his rich contacts was also always based on speculation. —Gilad Edelman, The Atlantic, 7 Feb. 2026

This monologue on housing theory was a roundabout way of explaining a photo of Censori with her mother, aunt, and sister, in which Censori looks like the daughter of a Real Housewife of New Jersey, with a clementine tan and leopard-print bustier. —Anna Peele, Vanity Fair, 6 Feb. 2026

The plan is to test her theory on an unsuspecting man in increasingly cringey ways. —Charlie Vargas, Oc Register, 6 Feb. 2026

Schauder’s theory wasn’t simply harder to prove in the nonuniform case. —Quanta Magazine, 6 Feb. 2026