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Synonyms

underground

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

adverb

  1. beneath the surface of the ground: ground.

    traveling underground by subway.

  2. in concealment or secrecy; not openly.

    subversion carried on underground.


adjective

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

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

adverb

  1. going below ground level

    the tunnel led underground

  2. into hiding or secrecy

    the group was driven underground

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. a space or region below ground level

    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

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

  3. (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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of underground

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

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.

A few weeks later, authorities detained the leaders of one of China’s most vibrant underground church networks, including Ezra Jin, a high-profile pastor.

From The Wall Street Journal

Beyond that, the Department of Water and Power is laying plans to put its electrical lines underground throughout the Palisades, a process expected to take years.

From Los Angeles Times

Kathrin Smetana, Assistant Professor in the Department of Mathematical Sciences at Stevens, explains that underground materials vary widely.

From Science Daily

As genre names go, “post-punk” is particularly hard to pin down, but it’s generally used to describe an array of underground rock forms that emerged in the late ’70s, mostly in the U.K.

From The Wall Street Journal

The British Ministry of Defence said it cooperated with France on Saturday night to strike an underground facility in Syria that had likely been used by the Islamic State group to store weapons.

From Barron's