underground

[uhn-der-ground, uhn-der-ground]

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

adjective

1. occurring, situated, or used below ground level

   an underground tunnel

   an underground explosion

2. secret; hidden

   underground activities

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

Word History and Origins

Origin of underground¹

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

Example Sentences

Villanueva downplayed the effectiveness of the thermal imaging cameras, noting that some chaparral in the city extends 15 to 25 feet underground, while the depth of the department’s cameras is only a foot.

Read more on Los Angeles Times

The underground space spanning some 5,000 square feet is, he explained, is "just like a little shelter, it's like a basement".

Read more on BBC

Even before Roan was one of the biggest pop stars on the planet, her reputation in underground queer nightlife was ascendant.

Read more on Los Angeles Times

Pieces of pottery and other evidence found inside the sprawling underground tomb revealed that it belonged to Thutmose II, a young pharaoh who died an untimely death more than three millennia ago.

Read more on The Wall Street Journal

The blaze, which firefighters had said was contained hours later, smoldered underground in dense vegetation for days until powerful winds on Jan. 7 caused it to spread, authorities said.

Read more on The Wall Street Journal

Related Words

• clandestine 
• experimental 
• hidden 
• private