underground
Americanadverb
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beneath the surface of the ground.
traveling underground by subway.
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in concealment or secrecy; not openly.
subversion carried on underground.
adjective
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existing, situated, operating, or taking place beneath the surface of the ground.
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used, or for use, underground.
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hidden or secret; not open.
underground political activities.
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published or produced by political or social radicals or nonconformists.
an underground newspaper.
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avant-garde; experimental.
an underground movie.
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critical of or attacking the established society or system.
underground opinion.
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of or for nonconformists; unusual.
an underground vegetarian restaurant.
noun
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the place or region beneath the surface of the ground.
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an underground space or passage.
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a secret organization fighting the established government or occupation forces.
He fought in the French underground during the Nazi occupation of France.
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(often initial capital letter) a movement or group existing outside the establishment and usually reflecting unorthodox, avant-garde, or radical views.
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Chiefly British. a subway system.
verb (used with object)
adjective
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occurring, situated, or used below ground level
an underground tunnel
an underground explosion
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secret; hidden
underground activities
adverb
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going below ground level
the tunnel led underground
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into hiding or secrecy
the group was driven underground
noun
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a space or region below ground level
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a movement dedicated to overthrowing a government or occupation forces, as in the European countries occupied by the German army in World War II
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( as modifier )
an underground group
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US and Canadian equivalent: subway. an electric passenger railway operated in underground tunnels
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(usually preceded by the)
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any avant-garde, experimental, or subversive movement in popular art, films, music, etc
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( as modifier )
the underground press
underground music
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Other Word Forms
Noun Inflected Forms
Etymology
Origin of underground
Vocabulary lists containing underground
Florida's B.E.S.T. Common Prefixes: under-
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Spelling Practice, Unit 1
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Secret
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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:
In an interview with Fox News on Tuesday morning, Trump was asked about reports that Netanyahu planned to present him with intelligence about new activity at Pickaxe Mountain, a suspected underground nuclear site in Iran.
From Los Angeles Times ● Jul. 28, 2026
Liz Muller said Deep Fission’s plan to store spent fuel underground is safe.
From The Wall Street Journal ● Jul. 28, 2026
That information may ultimately reveal more about the communities that produced the images and the cultural importance these underground spaces held over thousands of years.
From Science Daily ● Jul. 28, 2026
He said there should be an emphasis on "preserving natural field which provides habitat for insects, bugs, moths and caterpillars that need to incubate underground there."
From BBC ● Jul. 28, 2026
Knowing that the duke will welcome military expertise, Leonardo says that he’s an engineer who can dig underground tunnels.
From "The Mona Lisa Vanishes" by Nicholas Day
Glasgow and Budapest opened their undergrounds in 1896, as did Paris in 1900, New York in 1904, and Buenos Aires in 1913.
From Textbooks ● Dec. 14, 2022
This semester, Athey is teaching a class on subcultures and undergrounds at USC’s Roski School of Art and Design.
From Los Angeles Times ● Aug. 25, 2017
New York’s various undergrounds can make for a disciplined apprenticeship, and Gaga takes pride in her earliest fan base of art, fashion and music students.
From New York Times ● Oct. 17, 2016
But he remained a name known primarily to those whose knowledge of the city’s music was steeped in various undergrounds.
From Washington Post ● Jun. 23, 2015
In the darkness, where at first, after so much sunlight, the little electric lamps seem to us scarcely more than glow-worms, we expected a certain amount of chilliness as in the undergrounds of our climate.
From Egypt (La Mort de Philae) by Baines, William Peter
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.
