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
This process is thought to underlie decisions, thoughts, and memories, and studying it directly could help explain how the brain performs complex computations.
From Science Daily ● Dec. 29, 2025
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
One of Bernanke’s key recommendations was that policymakers should be clear when they as individuals don’t fully believe in the assumptions that underlie the central forecast.
From The Wall Street Journal ● Oct. 31, 2025
In particular, we know the basic laws that underlie all of chemistry and biology.
From "A Brief History of Time: And Other Essays" by Stephen Hawking
Keeping such power a safe distance from Israeli civilians underlies the thinking, and the subsequent action.
From The Wall Street Journal ● Jul. 12, 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
By contrast, her father’s hypervigilance also underlies the narrative.
From Los Angeles Times ● May 11, 2026
"And that motive likely underlies this launch as well," he added.
From Barron's ● Mar. 14, 2026
It might turn out that the same tendency underlies the joining of organisms into communities, communities into ecosystems, and ecosystems into the biosphere.
From "The Lives of a Cell" by Lewis Thomas
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
However, Sidony says her flooring was never inspected, and has shown the BBC her end of tenancy agreement which instructed her to remove carpets, underlay, gripper rods and laminate flooring.
From BBC ● Nov. 27, 2024
California created an orchard for the world in large part by tapping into prehistoric aquifers that underlay the Central Valley.
From Los Angeles Times ● Oct. 13, 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
I just wanted us to be talking and joking comfortably, like we were on the couch together back home, but some tension underlay everything.
From "The Fault in Our Stars" by John Green
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
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 region is underlain by quartz veins, rich in ore.
From Seattle Times ● May 22, 2023
The town is built on high ground underlain by solid limestone, and has much natural and architectural beauty.
From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 4 "Carnegie Andrew" to "Casus Belli" by Various
Still, the director’s contributions for the most part supported the underlying emotional drama, which, in lesser musical and theatrical hands, can be flattened into an evening of empty display.
From The Wall Street Journal ● Jul. 28, 2026
His underlying data and touchmaps suggest he is a penalty-box striker who has thrived in a fantastically well-coached system under Kjetil Knutsen.
From BBC ● Jul. 28, 2026
Higher rates can suppress demand; but they cannot fix the underlying supply shortage.
From MarketWatch ● Jul. 28, 2026
“We remain cautiously hopeful as we continue searching for the underlying cause of her illness.”
From Los Angeles Times ● Jul. 28, 2026
Pure mathematics does indeed deal with certainties, but its applications are only as good as the underlying empirical assumptions, simplifications, and estimations that go into them.
From "Innumeracy: Mathematical Illiteracy and Its Consequences" by John Allen Paulos
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.
