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:
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
"By uncovering how these microscopic regulators cooperate," Tolić says, "we are not only deepening our understanding of biology but also moving closer to correcting the failures that underlie disease."
From Science Daily ● Dec. 10, 2025
It was there he learned the Socratic method of inquiry by oral combat that would underlie both his remarkable achievements and the harsh judgments that would precipitate his fall from grace.
From Los Angeles Times ● Nov. 7, 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
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
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
"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
The new model is going up against OpenAI’s GPT-5, the latest AI which underlies its ChatGPT app.
From Barron's ● Nov. 19, 2025
Linguists term this decisive innovation, which also underlies puns today, the rebus principle.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
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
He stood on the edge of the sandrock shelf that underlay Laguna and looked east across the river before dawn.
From "Ceremony:" by Leslie Marmon Silko
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
Isobel had been less blunt in her methods, but a corrosive acid had underlain her gentle speech.
From The Moon out of Reach by Pedler, Margaret
“This could be a warning sign of other underlying conditions that we can actually treat.”
From The Wall Street Journal ● Jul. 31, 2026
At this stage in his lauded career, Bardem is interested only in roles that explore “contradictions with an underlying humanity.”
From Los Angeles Times ● Jul. 31, 2026
It raised the target to a three-decade high in June, citing the possibility that underlying inflation could exceed its 2% target.
From The Wall Street Journal ● Jul. 31, 2026
Whatever the Supreme Court decides after the states’ deadline next week, the underlying tension is worth sitting with.
From Slate ● Jul. 30, 2026
In fact, I began to sense a greater underlying pattern to the way the wind moved through the courtyard.
From "The Name of the Wind" by Patrick Rothfuss
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.
