theoretical
Americanadjective
-
of, relating to, or consisting in theory; not practical (distinguished from applied).
-
existing only in theory; hypothetical.
-
given to, forming, or dealing with theories; speculative.
adjective
-
of or based on theory
-
lacking practical application or actual existence; hypothetical
-
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
Compare meaning
How does theoretical compare to similar and commonly confused words? Explore the most common comparisons:
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
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!
Unit 2: Pivotal Words and Phrases
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!
Unit 2: Pivotal Words and Phrases
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!
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 experimental findings were supported by first-principles calculations based on density functional theory, performed by a theoretical team led by Dr. Maia G. Vergniory of the Donostia International Physics Center and Université de Sherbrooke.
From Science Daily • Jun. 5, 2026
Yale economist Robert Shiller has been widely credited with laying much of the theoretical groundwork for perpetual futures.
From MarketWatch • Jun. 5, 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
While much of this field is still theoretical, Google says Willow incorporates key "breakthroughs" and "paves the way to a useful, large-scale quantum computer".
From BBC • May 28, 2026
Their speculations were purely abstract and theoretical; they applied to any possible world and not to our actual world.
From "The Invention of Science" by David Wootton
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.
