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

Some of these signals are consistent with magnetic interactions between stars and their planets—an effect long predicted by theory but rarely observed directly. —Rupendra Brahambhatt, Interesting Engineering, 1 Feb. 2026

Democrats wringing their hands and making appeals to process while the President sends people to Salvadoran prisons without trial are unfit to meet the moment, this theory says. —Nathan Heller, New Yorker, 1 Feb. 2026

From the box office data alone, and from where Melania played, the odds are against any theory that a great degree of juicing went on at the box office. —Anthony D'alessandro, Deadline, 1 Feb. 2026

The active theory was that the assailants were career burglars or career thugs or worse. —Scott Eden, Rolling Stone, 1 Feb. 2026