theoretical
Americanadjective
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of, relating to, or consisting in theory; not practical (distinguished from applied).
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existing only in theory; hypothetical.
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given to, forming, or dealing with theories; speculative.
adjective
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of or based on theory
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lacking practical application or actual existence; hypothetical
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using or dealing in theory; impractical
Other Word Forms
Derived Forms
Etymology
Origin of theoretical
First recorded in 1610–20; theoretic, from Late Latin theōrēticus, from Greek theōrētikós, equivalent to theōrēt(ós) “to be seen” (verbal adjective derived from theōreîn “to view”) + -ikos -ic; see -al 1
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Explanation
Something theoretical is concerned with theories and hypotheses — it's not necessarily based on real life or meant to be applied to real life. Theoretical things are based on theory and ideas, while practical ones are based on practice. Theoretical thinking can be really helpful when you're trying to imagine something or problem-solve, but your theories should always be tested out in the practical world. As philosopher Bertrand Russell said, “The theoretical understanding of the world, which is the aim of philosophy, is not a matter of great practical importance to animals, or to savages, or even to most civilized men.”
Vocabulary lists containing theoretical
Albert Einstein
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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.
It also aims to “accelerate the economy” and give “everyone on Earth” access to personal artificial general intelligence, or AGI, a theoretical AI that can operate at or above a human level.
From MarketWatch • Jun. 8, 2026
All of that said, we should note the governor’s race has yet to be officially decided and Steyer still has at least a theoretical possibility of slipping into the top two.
From Los Angeles Times • Jun. 7, 2026
"Through this theoretical framework, we found that we can use small physical boundaries up to ten meters to perturb ocean transport barriers that spans kilometers," said Fang.
From Science Daily • Jun. 3, 2026
The paper claimed the first discovery of a Majorana fermion, a theoretical particle central to the tech giant’s quantum computing effort.
From Barron's • Jun. 3, 2026
They are interested solely in confirming highly dubious theoretical hypotheses by the logic of analogy and induction, and make no attempt at refutation or intersubjective testing.’
From "The Chosen" by Chaim Potok
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
