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

Prosecutors claimed the line bolstered their theory that Banks was attempting to flee the country at the time of his arrest. — Nancy Dillon, Rolling Stone, 13 Aug. 2026

Basic economic theory says landowners would wait for others to spend the time, money and energy to control hogs – which means nobody does, and the problems grow. — Aaron Smith, The Conversation, 13 Aug. 2026

Nelson’s mind quickly sails from cold floor-pragmatics to high theory. — Literary Hub, 13 Aug. 2026

The theory advanced by Gruden is that Goodell or someone in the commissioner’s office leaked the emails to damage Gruden’s reputation. — Michael McCann, Sportico.com, 12 Aug. 2026