underbelly
Americannoun
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the lower abdomen; posterior ventral area, as of an animal's body.
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the lower surface of an object; underside.
the underbelly of an airplane.
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a vulnerable area; weak point.
an attack on the soft underbelly of Europe.
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a dark, seamy, often hidden area or side.
a police officer continually exposed to the underbelly of society.
noun
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the part of an animal's belly nearest to the ground
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a vulnerable or unprotected part, aspect, or region
Other Word Forms
Noun Inflected Forms
Etymology
Origin of underbelly
Explanation
The underbelly of something is its secret weakness, something about it that's not protected from harm. Once a computer hacker discovers a network's underbelly, they're easily able to hack into it. Literally, an underbelly is just that: it's the abdomen of an animal, the soft lower belly. Often, that's also the most vulnerable part of an animal's body, since it contains major organs, and it's where the figurative meaning comes from. An alternate informal definition is "a hidden, criminal part of society," like the underbelly of a city where criminals trade stolen goods.
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:
While the now-replaced aircraft sported a blue and white exterior, the new aircraft has a navy blue underbelly, thin red stripe and blue upper body.
From Barron's ● Jun. 19, 2026
It also exposed the AI boom’s underbelly: the grubby sidedeals, financial anxieties, short tempers and personal vendettas that have shaped modern technology every bit as much as the march toward machine consciousness.
From The Wall Street Journal ● May 16, 2026
Because people like to say things like, “If I became a right-wing influencer I’d get so rich,” and while there is some truth to that, there is this underbelly of people with really marginal influence.
From Slate ● May 7, 2026
Lane’s Willy is both a paternal tyrant and a wounded bear, growling if anyone interrupts him yet unable to conceal his soft underbelly.
From Los Angeles Times ● Apr. 29, 2026
They lined the underbelly of the building’s colossal cathedral ceiling like glowing slices of pie.
From "Mr. Lemoncello's Library Olympics" by Chris Grabenstein
Oseguera González’s counsel responded by telling jurors they should be skeptical of key witnesses “who have made that deal with the government” — an arrangement that he called “one of the underbellies of criminal justice.”
From Los Angeles Times ● Sep. 18, 2024
With creamy white underbellies and an unmistakable crown of shaggy feathers, a Philippine eagle makes a regal impression.
From National Geographic ● Jan. 28, 2021
The clouds that brooded over Knoxville on Thursday looked like 4-8 clouds, and some had dark underbellies, making them clearly 0-8-in-the-Southeastern Conference clouds.
From Washington Post ● Dec. 8, 2017
House mice have solid colors, but deer mice range from gray to reddish brown, with white on their underbellies and sides of their tails.
From Seattle Times ● Aug. 31, 2012
Thunder grumbled over the ocean and lightning lit the underbellies of the clouds, flashing from sea to sky and back again.
From "Ship Breaker" by Paolo Bacigalupi
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.
