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

Another theory is that attacking the BBC plays well among populist voters at a time when Labour is losing support to Reform, the party led by Nigel Farage, a staunch ally of Donald Trump. —Jake Kanter, Deadline, 9 July 2025

At the end of the appointment, my dentist relayed a theory that more than over-enthusiastic brushing could wear out enamel at the gumline. —Denise Snodell, Kansas City Star, 9 July 2025

Patel and Bongino are among those who had pushed such theories before joining the government. —Sarah Fortinsky, The Hill, 9 July 2025

During May 15 oral arguments, none of the justices voiced support for the Trump administration’s theory that the president’s order is consistent with the 14th Amendment’s citizenship clause and past Supreme Court decisions about that provision. —Sara Chernikoff, USA Today, 28 June 2025