underground

American  

[uhn-der-ground, uhn-der-ground] / ˈʌn dərˈgraʊnd, ˈʌn dərˌgraʊnd /

adverb

1. beneath the surface of the ground.

   traveling underground by subway.

2. in concealment or secrecy; not openly.

   subversion carried on underground.

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adjective

1. existing, situated, operating, or taking place beneath the surface of the ground.

2. used, or for use, underground.

3. hidden or secret; not open.

   underground political activities.

4. published or produced by political or social radicals or nonconformists.

   an underground newspaper.

5. avant-garde; experimental.

   an underground movie.

6. critical of or attacking the established society or system.

   underground opinion.

7. of or for nonconformists; unusual.

   an underground vegetarian restaurant.

noun

• undergrounds
  plural

1. the place or region beneath the surface of the ground.

2. an underground space or passage.

3. a secret organization fighting the established government or occupation forces.

   He fought in the French underground during the Nazi occupation of France.

4. (often initial capital letter) a movement or group existing outside the establishment and usually reflecting unorthodox, avant-garde, or radical views.

5. Chiefly British. a subway system.

verb (used with object)

1. to place beneath the surface of the ground.

   to underground utility lines.

underground British  

adjective

1. occurring, situated, or used below ground level

   an underground tunnel

   an underground explosion

2. secret; hidden

   underground activities

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adverb

1. going below ground level

   the tunnel led underground

2. into hiding or secrecy

   the group was driven underground

noun

1. a space or region below ground level

2. 1. a movement dedicated to overthrowing a government or occupation forces, as in the European countries occupied by the German army in World War II

   2. ( as modifier )

      an underground group

3. US and Canadian equivalent: subway.  an electric passenger railway operated in underground tunnels

4. (usually preceded by the)

   1. any avant-garde, experimental, or subversive movement in popular art, films, music, etc

   2. ( as modifier )

      the underground press

      underground music

Other Word Forms

Noun Inflected Forms

• undergrounds
  plural

Etymology

Origin of underground

First recorded in 1565–75; under- + ground ¹

Example Sentences

See Examples For:

underground undergrounds

Peatlands have proved problematic for wildfires because the fire can spread through the peat, deep underground as well as on the surface.

From BBC ● Aug. 25, 2026

In 2006 it was confirmed that North Korea had successfully conducted an underground nuclear test and was on its way to building a bomb.

From Salon ● Aug. 23, 2026

What archaeologists do know is that the vessel survived for centuries underground before University of Florida students uncovered it earlier this year, still completely intact.

From Science Daily ● Aug. 22, 2026

A district court ordered a halt to work on the aboveground ballroom while allowing construction of the underground military bunker to proceed, but that order had been stayed while on appeal.

From Barron's ● Aug. 21, 2026

There were seven seated at the table, a Jewish couple waiting placement and three underground workers in addition to Father and Betsie.

From "The Hiding Place" by Corrie ten Boom

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

Joining her in conversation is Luc Sante, a critic known for his journalistic exploration of urban undergrounds; his most recent book, “The Other Paris,” gives similar treatment to the City of Light.

From New York Times ● Jan. 21, 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

"I'm never sure where these French undergrounds are going to land me."

From The Triflers by Frederick Orin Bartlett

Related Words

• clandestine
• experimental
• hidden
• private