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
Saleen Martin, USA TODAY, 5 Dec. 2024
In recent years, California’s power companies have been doing just that: insulating power lines and burying lines underground, trimming trees, deploying drones and using risk-detection technology.
—Calmatters, The Mercury News, 4 Dec. 2024
Jonah Walters, Longreads, 24 Oct. 2024
Even before the country’s founding in 1948, the Zionist underground movement assassinated British military officers and police, seeing them as obstacles to creating a Jewish state.
—Dan De Luce, NBC News, 20 Sep. 2024
Reuters, CNN, 10 Dec. 2024
The trial proceedings, moved to a secure underground Tel Aviv courtroom, highlight Netanyahu's unique position as the first Israeli prime minister to testify as a criminal defendant.
—Paul Du Quenoy, Newsweek, 9 Dec. 2024
See all Example Sentences for underground 
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Adverb
Their nests are usually underground though, as well as near roots of large trees.
—Saleen Martin, USA TODAY, 5 Dec. 2024
In recent years, California’s power companies have been doing just that: insulating power lines and burying lines underground, trimming trees, deploying drones and using risk-detection technology.
—Calmatters, The Mercury News, 4 Dec. 2024
Noun
During the call, my dad reminisced about his childhood on an Air Force base in New Mexico, where everyone would gather overnight in a vast underground bunker during fallout drills.
—Jonah Walters, Longreads, 24 Oct. 2024
Even before the country’s founding in 1948, the Zionist underground movement assassinated British military officers and police, seeing them as obstacles to creating a Jewish state.
—Dan De Luce, NBC News, 20 Sep. 2024
Adjective
The trial was moved from Jerusalem for undisclosed security reasons and convened in an underground courtroom.
—Reuters, CNN, 10 Dec. 2024
The trial proceedings, moved to a secure underground Tel Aviv courtroom, highlight Netanyahu's unique position as the first Israeli prime minister to testify as a criminal defendant.
—Paul Du Quenoy, Newsweek, 9 Dec. 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 23 Dec. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share