underground

[ adverb uhn-der-ground; adjective noun verb 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. the underground
   an electric passenger railway operated in underground tunnels US and Canadian equivalentsubway
4. usually preceded by the
   1. any avant-garde, experimental, or subversive movement in popular art, films, music, etc
   2. ( as modifier )

      underground music

      the underground press

Word History and Origins

Origin of underground¹

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

Example Sentences

Sinkholes can be formed by gradual dissolution happening underground, but they can also be caused by heavy rain or surface flooding, construction work, leaking drainage pipes, burst water mains and groundwater abstraction, the BGS said.

From BBC

"It's refreshing that someone's going to the underground for new sounds," he says.

From BBC

Renovation work at Notre-Dame has been a boon for archaeologists, who have been able to access underground areas that date back to hundreds of years before the cathedral was built.

From BBC

Nearly $20 million will go to electrify the university’s BruinBus fleet and install underground charging for shuttles and buses along a route that stretches for less than a mile in Westwood.

From Los Angeles Times

It happened close to where an underground natural gas leak occurred in July following the installation of a ground source heat pump.

From BBC

Related Words

• clandestine
• experimental
• hidden
• private