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

Sticking faithfully to a theory is praised as strength, a badge of consistency. —Shai Tubali, Big Think, 30 Sep. 2025

Some theories propose a colossal asteroid impact redistributed the moon’s interior, while others suggest the moon once had a smaller sibling that merged unevenly, enriching the near side with heat-producing elements. —Samantha Mathewson, Space.com, 30 Sep. 2025

No credible evidence The best explanation of the weakness of that theory comes from Andrew McCarthy, a former federal prosecutor and my friend and former colleague at National Review. —David French, Mercury News, 30 Sep. 2025

According to the researchers, the sharp and sudden rise in brightness rules out existing theories regarding the little red dots. —Chris Young, Interesting Engineering, 30 Sep. 2025