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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.

One theory believed to be part of the investigation is that the school, next to an Islamic Revolutionary Guards Corps base, could have been hit as a result of outdated intelligence.

From BBC • Apr. 3, 2026

“There’s this huge game theory incentive to be the first one to leave versus stick around, even if you think the fundamentals are fine,” said Brian Jacobs, a portfolio manager at Aptus Capital Advisors.

From The Wall Street Journal • Apr. 2, 2026

But this theory is entirely false, based on hastily assembled “academic” work that’s riddled with errors and lies.

From Slate • Apr. 1, 2026

Round number theory then came into play at $30 with a bearish shooting star candle on March 19.

From Barron's • Mar. 31, 2026

In theory the Vanguard should have made it into orbit.

From "Reaching for the Moon" by Katherine Johnson

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.