underground
Americanadverb
adjective
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existing, situated, operating, or taking place beneath the surface of the ground. 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. 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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Etymology
Origin of underground
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.
Loudoun County was already home to extensive underground cable and an internet exchange point, even drawing AOL’s headquarters in the 1990s.
In Romania, researchers recently examined a bacterial strain that had been trapped in a 5,000-year-old layer of ice inside an underground cave.
From Science Daily
The reports, by the city and the global infrastructure firm AECOM, also recommended that the city complete significant brush clearance work, bolster its water system and move electrical wires underground.
From Los Angeles Times
The harsh environment would confine people to domes or underground shelters, where boredom and isolation would be real dangers.
Toxic gas is believed to have built up underground in poorly ventilated tunnels, causing the workers to collapse just before the end of their night shift.
From BBC
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.