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

Swipe it on and then start formulating your own beauty theories. — Kara Nesvig, Allure, 15 Sep. 2026

Well, there’s a running number of theories with only some consensus. — Maya Georgi, Rolling Stone, 15 Sep. 2026

The result would turn up more than 20 years later as On the Origin of Species, Darwin’s seminal work explaining the theory of evolution through natural selection. — Michele Metych Britannica Editors Sep. 14, Encyclopedia Britannica, 14 Sep. 2026

The prevailing theory is that Icelandic winters are notoriously variable, which wreaks havoc on the dormant phase of Arctic mosquitoes’ life cycle, killing eggs in unpredictable freezes and thaws. — Mark Sappenfield, Christian Science Monitor, 14 Sep. 2026