underground

American  

[uhn-der-graund, uhn-der-graund] / 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

But while AI could boost the efficiency and use of renewables, the technology has long been used by oil and gas companies to sift through geological data, identify underground reservoirs and streamline fossil fuel production.

From Barron's ● Oct. 15, 2026

Your meal might involve entering a whimsical Italian restaurant through a bathroom, or eating a 10-course menu of fine Korean food at a former underground barbershop.

From Slate ● Oct. 13, 2026

Jordan Firstman’s sincere, funny and genuinely moving debut feature has him playing a queer New York underground party promoter blindsided by the arrival of the 10-year-old son previously unknown to him.

From Los Angeles Times ● Oct. 12, 2026

The soggy ground, along with acidification, prevents the underground matter from decomposing completely as it is slowly pickled into peat.

From The Wall Street Journal ● Oct. 9, 2026

“Get away!” he would say, and he would chase off the cats, the birds, the occasional mouse or rat on the underground.

From "Impossible Creatures" by Katherine Rundell

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 William Peter Baines

Related Words

• clandestine
• experimental
• hidden
• private