underlie
Americanverb (used with object)
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to lie under or beneath; be situated under.
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to be at the basis of; form the foundation of.
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Grammar. to function as the root morpheme or original or basic form of (a derived form).
The form “boy” underlies “boyish.”
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Finance. to be primary to another right or security.
verb
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to lie or be placed under or beneath
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to be the foundation, cause, or basis of
careful planning underlies all our decisions
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finance to take priority over (another claim, liability, mortgage, etc)
a first mortgage underlies a second
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to be the root or stem from which (a word) is derived
"happy" underlies "happiest"
Other Word Forms
Derived Forms
Inflected Forms
Participles
Conjugated Forms
Present
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underliesimple
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underliessimple
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have underlainperfect
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has underlainperfect
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am underlyingprogressive
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are underlyingprogressive
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is underlyingprogressive
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have been underlyingperfect progressive
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has been underlyingperfect progressive
Past
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underlaysimple
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had underlainperfect
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was underlyingprogressive
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were underlyingprogressive
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had been underlyingperfect progressive
Future
Etymology
Origin of underlie
before 900; Middle English underlyen (v.), Old English underlicgan. See under-, lie 2
Explanation
While it’s true that when something underlies something else, it is beneath it, this does not necessarily mean subservience — it can also indicate a strong foundation or bedrock that underlies, or supports, an idea or decision. The Old English word underlicgan meant to serve or submit to another, and that meaning does carry through to the modern word underlie — to a point. Although still referring to something under something else, around 1850 the meaning of the verb shifted to include something that makes a foundation for something else. For example, one factor that underlies a patient's unusual symptoms might be his recent trip to a foreign country, where he could have picked up a local infection.
Vocabulary lists containing underlie
The Thing About Jellyfish
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"The Hand of Fatima" and "Old Ways, New World"
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Florida's B.E.S.T. Common Prefixes: under-
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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.
See Examples For:
“The paintings are about the smoldering tensions that underlie the American dream, so I think it’s a particularly apt moment to bring them back into the public eye.”
From Los Angeles Times ● Jun. 9, 2026
True open-source models allow full access to training data and code, while open-weight models share the numerical parameters, or “weights,” that underlie them.
From The Wall Street Journal ● Mar. 18, 2026
"A similar mechanism could underlie individual differences in responses to other rewarding stimuli," says author and neuroscientist Josep Marco-Pallarés of the University of Barcelona.
From Science Daily ● Jan. 12, 2026
Talk to some folks in your family whom you trust to make sure you’re not overstepping any unspoken boundaries that underlie family relationships.
From MarketWatch ● Dec. 15, 2025
This fact creates double difficulties for efforts to test the hypothesis that intellectual differences underlie technological differences.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
That conviction underlies Christian accounts of dignity, equality, justice and human responsibility.
From The Wall Street Journal ● Jul. 9, 2026
But five days after that, the DOJ notified the court in the Texas case that “the government has decided to maintain the definition” that underlies the ghost gun rule.
From Salon ● Jun. 2, 2026
"And that motive likely underlies this launch as well," he added.
From Barron's ● Mar. 14, 2026
"These results reveal that a shared genetic programme conserved throughout evolution underlies the specialisation of macrophages across tissues," adds Domien Vanneste, first author of the scientific article.
From Science Daily ● Mar. 1, 2026
Any racial justice movement, to be successful, must vigorously challenge the public consensus that underlies the prevailing system of control.
From "The New Jim Crow" by Michelle Alexander
In postproduction, Del Toro sometimes underlay Elordi’s screams with his own guttural noises or the roars of lions and gorillas, imagining a voice created by mismatched lungs and a throat from different people.
From The Wall Street Journal ● Sep. 30, 2025
It is more breathable but is often installed where a highly-resistant underlay like bitumen felt is already present, stopping vapour from escaping.
From BBC ● Nov. 17, 2024
The turf was intended to function as an underlay for a plastic liner atop it as part of a construction project.
From Seattle Times ● Nov. 22, 2023
There is a strong likelihood that what underlay the claims for the Grave Creek Stone were assumptions that impressive archaeological sites in North America could not possibly be the work of Native Americans.
From Slate ● Nov. 11, 2023
Over time, observation became an adjunct to experiment, both producing reliable facts in place of the unreliable, unspecific ‘experience’ which underlay so much classical and medieval discussion.
From "The Invention of Science" by David Wootton
A fundamental tension has always underlain the history of the Civil Rights movement, much as it did contemporaneous news coverage.
From The Wall Street Journal ● May 3, 2026
Part of the reasoning in 2018 was site investigations found the ground underlain with peat deposits, as well as toxic and phytotoxic - meaning poisonous to plants - risk from shallow soils.
From BBC ● Nov. 15, 2025
Approximately 91 per cent of these forests in the northern hemisphere are underlain by permafrost.
From Science Daily ● Nov. 9, 2023
The drill site in northwest Greenland was 138 miles from the coast and underlain by 4,560 feet of ice.
From Salon ● Jul. 23, 2023
The Fens on the eastern side of the county are underlain by Oxford clay, which here and there projects through the prevailing newer deposit of silt and loam.
From Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 8 "Hudson River" to "Hurstmonceaux" by Various
He says the underlying physics was first shown in simple models decades ago and has appeared repeatedly since.
From BBC ● Jul. 14, 2026
The goal is to help clinicians monitor biological aging more precisely and design individualized treatments that target the underlying causes of age-related disease.
From Science Daily ● Jul. 14, 2026
If this trade is left unhedged, an investor who has sold yen can benefit from both dollar appreciation and gains on the underlying investments, such as U.S. tech stocks.
From MarketWatch ● Jul. 14, 2026
“Even if attacks subside temporarily, the underlying dispute over the strait will remain, making future flare-ups highly likely.”
From The Wall Street Journal ● Jul. 13, 2026
By then the underlying structure of my face would be set and I’d have plenty of time to recover before school.
From "Ugly" by Robert Hoge
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.
