underground

1 of 3

adverb

un·​der·​ground ˌən-dər-ˈgrau̇nd 

1

: beneath the surface of the earth

2

: in or into hiding or secret operation

underground

2 of 3

noun

ˈən-dər-ˌgrau̇nd 

1

: a subterranean space or channel

2

: an underground city railway system

3

a

: a movement or group organized in strict secrecy among citizens especially in an occupied country for maintaining communications, popular solidarity, and concerted resistive action pending liberation

b

: a clandestine conspiratorial organization set up for revolutionary or other disruptive purposes especially against a civil order

c

: an unofficial, unsanctioned, or illegal but informal movement or group

especially : a usually avant-garde group or movement that functions outside the establishment

underground

3 of 3

adjective

un·​der·​ground ˈən-dər-ˌgrau̇nd 

1

: being, growing, operating, or situated below the surface of the ground

2

: conducted by secret means

3

a

: existing outside the establishment

an underground literary reputation

b

: existing outside the purview of tax collectors or statisticians

the underground economy

4

a

: produced or published outside the establishment especially by the avant-garde

underground movies

underground newspapers

b

: of or relating to the avant-garde underground

an underground moviemaker

an underground theater

Synonyms

Noun

• resistance

Adjective

• backstairs
• behind-the-scenes
• clandestine
• covert
• furtive
• hole-and-corner
• hugger-mugger
• hush-hush
• private
• privy
• secret
• sneak
• sneaking
• sneaky
• stealth
• stealthy
• surreptitious
• undercover
• underhand
• underhanded

Examples of underground in a Sentence

Adverb

They had been living underground as fugitives.

Noun

I've ridden on the New York subway, the Paris Metro, and the London Underground.

joined the underground while still a teenager

Adjective

The drugs are supplied through an underground network.

She loves the city's underground music scene.

Recent Examples on the Web

Adverb

That’s why officials chose the single-bore solution, which tunnels underground with minimal surface disruption. —Dan Phan, The Mercury News, 12 Nov. 2024

The crew scans as underground but is now flirting with mainstream rap culture, thanks to their gold and platinum plaques, billions of streams, and an aura that any major rap or popstar would sell their soul to have. —Alphonse Pierre, Pitchfork, 4 Nov. 2024

Noun

Paul Morrissey, a fixture of New York’s cinema scene whose collaborations with Andy Warhol in the ’60s and ’70s reinvented the American underground and made local legends of amateur actors and transgender performers, died Monday at a hospital in Manhattan. —J. Kim Murphy, Variety, 28 Oct. 2024

To ensure that shooting the CO2 underground doesn’t inadvertently contaminate drinking water sources, the EPA has to issue permits for the new wells under the Safe Drinking Water Act Underground Injection Control program. —Justine Calma, The Verge, 5 Sep. 2024

Adjective

It is feared that inside some of the vehicles that were washed away or trapped in underground garages there could be bodies waiting to be recovered. —Hernán Muñoz and Joseph Wilson, Los Angeles Times, 5 Nov. 2024

Security forces have been searching for victims in ravines and underground garages, including a large parking lot at the Bonaire shopping center in Aldaia. —Atika Shubert, CNN, 4 Nov. 2024

Word History

First Known Use

Adverb

14th century, in the meaning defined at sense 1

Noun

1594, in the meaning defined at sense 1

Adjective

1601, in the meaning defined at sense 1

Phrases Containing underground

• go underground
• the underground

Kids Definition

underground

1 of 3 adverb

un·​der·​ground ˌən-dər-ˈgrau̇nd 

1

: below the surface of the ground

an underground passage

2

: in or into hiding or secret operation

the political party went underground

underground

2 of 3 noun

un·​der·​ground

ˈən-dər-ˌgrau̇nd

1

: a space under the surface of the ground

especially : subway sense 2

2

: a secret political group

especially : an organized body working in secret to overthrow a government or an occupying power

underground

3 of 3 adjective

un·​der·​ground ˈən-dər-ˌgrau̇nd 

1

: being, growing, operating, or located below the surface of the ground

an underground stream

2

: conducted secretly