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
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.
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
Everything points back in the direction of Angel Studios — or, really, the underbelly beneath it.
From Salon • May 3, 2026
“Fargo” found its humor in the juxtaposition between “Minnesota Nice” and the dark, criminal underbelly it explored.
From Los Angeles Times • Apr. 17, 2026
Maybe it was the underbelly of all of the bravado and power-seeking—some desire to counter all the validation with the humiliation of knowing that, deep down, he’s just a revolting little worm.
From Slate • Apr. 15, 2026
But no, it’s a storm petrel with its wide black wings, soft gray underbelly.
From "Sparrow" by Sarah Moon
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.
