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
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.
Dr. Fauci chimed in: “There are no data or theoretical reason to believe that vaccinating early versus later in pregnancy would be preferred.”
From The Wall Street Journal ● Aug. 13, 2026
Superintelligence is a theoretical point when AI's capabilities exceed human intelligence.
From Barron's ● Aug. 11, 2026
The researchers tested both their theoretical predictions and the new concentrator during an outdoor experiment at MPL.
From Science Daily ● Aug. 8, 2026
To determine how the system worked, the researchers combined in situ spectroscopy, photochemical analysis, finite element simulations, and theoretical calculations.
From Science Daily ● Aug. 6, 2026
At the other end of the table were various histories, theoretical treatises and practical handbooks on landscape gardening.
From "Atonement" by Ian McEwan
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.
