un·der·ground
ˌən-dər-ˈgrau̇nd 
1
: beneath the surface of the earth
2
: in or into hiding or secret operation
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
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
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
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
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
Joshua Siskin, Orange County Register, 14 Nov. 2024
De Menezes was on his way to repair a broken fire alarm when he was shot and killed in an underground carriage at Stockwell station.
—Irenie Forshaw, theweek, 12 Nov. 2024
See all Example Sentences for underground 
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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
Both lily turf and Natal lily spread by underground rhizomes so their territory in the garden will expand from year to year.
—Joshua Siskin, Orange County Register, 14 Nov. 2024
De Menezes was on his way to repair a broken fire alarm when he was shot and killed in an underground carriage at Stockwell station.
—Irenie Forshaw, theweek, 12 Nov. 2024
See all Example Sentences for underground
Dictionary Entries Near underground
Cite this Entry
“Underground.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/underground. Accessed 26 Nov. 2024.
Copy CitationKids 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
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