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
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
Spencer Kimball, CNBC, 11 Mar. 2025
The performance space, known as Big Mouth Cave, is 333 feet underground.
—Colleen Creamer, Chicago Tribune, 5 Mar. 2025
August Brown, Los Angeles Times, 1 Mar. 2025
Gordon, who is also a health and wellness coach, has spent the last five-plus years in the psychedelic underground working primarily with people who experience chronic pain.
—Christine Ricciardi, Boston Herald, 25 Feb. 2025
Francesca Aton, ARTnews.com, 13 Mar. 2025
But where Sematary drew inspiration from underground rap, Ghost Mountain’s earliest obsessions were indie bands like Modest Mouse and the Unicorns, whose anxious songs and caterwauling vocals struck a chord somewhere between naive and degenerate.
—Meaghan Garvey, Pitchfork, 13 Mar. 2025
See All Example Sentences for underground
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Adverb
The technology captures carbon dioxide emissions from industrial sites and stores them deep underground.
—Spencer Kimball, CNBC, 11 Mar. 2025
The performance space, known as Big Mouth Cave, is 333 feet underground.
—Colleen Creamer, Chicago Tribune, 5 Mar. 2025
Noun
Their instantly arresting look pulled from David Bowie’s androgyny and the drag-culture underground in New York.
—August Brown, Los Angeles Times, 1 Mar. 2025
Gordon, who is also a health and wellness coach, has spent the last five-plus years in the psychedelic underground working primarily with people who experience chronic pain.
—Christine Ricciardi, Boston Herald, 25 Feb. 2025
Adjective
The commuter hall is reminiscent of that of the original station, complete with high ceilings, iron and glass entrances, and a replica of the original clock; it would be connected within the James A. Farley Post Office via an underground tunnel to Moynihan Train Hall.
—Francesca Aton, ARTnews.com, 13 Mar. 2025
But where Sematary drew inspiration from underground rap, Ghost Mountain’s earliest obsessions were indie bands like Modest Mouse and the Unicorns, whose anxious songs and caterwauling vocals struck a chord somewhere between naive and degenerate.
—Meaghan Garvey, Pitchfork, 13 Mar. 2025
See All Example Sentences for underground
Cite this Entry
“Underground.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/underground. Accessed 25 Mar. 2025.
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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