Definitions

theory

[thee-uh-ree, theer-ee] / ˈθi ə ri, ˈθɪər i /

NOUN

hypothesis, belief

Synonyms

STRONGEST

approach argument assumption code concept doctrine idea ideology method philosophy plan position premise proposal provision rationale scheme speculation suspicion system thesis understanding

STRONG

base basis codification conditions conjecture dogma feeling foundation grounds guess guesswork hunch impression outlook postulate presentiment presumption shot stab supposal supposition surmise theorem

WEAK

formularization suppose systemization

Antonyms

STRONGEST

disbelief fact information reality truth

STRONG

calculation knowledge measurement proof

WEAK

certainty

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The base fee also protects the customer, in theory, from being overcharged.

From MarketWatch • Jun. 10, 2026

“I had to ask ChatGPT to explain block theory to me,” he says.

From Los Angeles Times • Jun. 9, 2026

Few ideas in modern science have reshaped our understanding of reality more profoundly than space-time — the interwoven fabric of space and time at the heart of Albert Einstein’s theory of relativity.

From Science Daily • Jun. 8, 2026

And the Mitchell wicket went against a theory held by this England regime that a certain style of cricket cannot be successful in the Test arena.

From BBC • Jun. 6, 2026

In the decades after the Mona Lisa theft, this theory would get compressed.

From "The Mona Lisa Vanishes" by Nicholas Day

Vocabulary lists containing theory

The Vocabulary.com Top 1000

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

The SAT: Language of the Test, List 6

Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!

The New SAT: The Language of the Test

Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!