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, which refers to the ancient Greek war between Sparta and Athens, describes the tendency toward conflict when an emerging power threatens an existing power. —Jeremy Mikula, NBC news, 16 May 2026

Waters defended the original strategy, saying that both Judge Clifton Newman and the Supreme Court accepted the logic of the state’s motive theory. —Sarah Rumpf-Whitten , Julia Bonavita, FOXNews.com, 16 May 2026

In the mid-1990s, DNA testing helped investigators eliminate the fingernail theory. —Christina Coulter, PEOPLE, 16 May 2026

In theory, that could give eBay sellers a bigger network for fulfilling orders and authenticating collectibles. —Allison Morrow, CNN Money, 5 May 2026