underground

1 of 3

adverb

un·​der·​ground ˌən-dər-ˈgrau̇nd How to pronounce underground (audio)
1
: beneath the surface of the earth
2
: in or into hiding or secret operation

underground

2 of 3

noun

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 How to pronounce underground (audio)
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
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
Mines were buried underground for concealment, unless the minefield was laid in a hurry when might be simply placed on the surface. David Hambling, Forbes.com, 3 Apr. 2025 The team of Egyptian and American archaeologists found the tomb, which the researchers estimate is 3,600 years old, nearly 23 feet underground at Abydos, one of the oldest cities of ancient Egypt. Alan Yuhas, New York Times, 27 Mar. 2025
Noun
In the ever-evolving cyber underground, ransomware extortionists have grown to become perhaps the most sophisticated and formidable threat. Etay Maor, Forbes.com, 26 Mar. 2025 Today’s underground will look very different in 10 years, as soil profiles shift, trees grow, animals tunnel, and people dig and build. IEEE Spectrum, 10 Mar. 2025
Adjective
This week, Alphonse grapples with the yearning for the 2000s in UK underground rap videos. Alphonse Pierre, Pitchfork, 21 Mar. 2025 Trending Video Margot Robbie Takes You Inside The Barbie Dreamhouse Despite the clever solutions for natural light underground, structural challenges loomed large. Kristen Flanagan, Architectural Digest, 19 Mar. 2025 See All Example Sentences for underground

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

Time Traveler
The first known use of underground was in the 14th century

Browse Nearby Words

Cite this Entry

“Underground.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/underground. Accessed 8 Apr. 2025.

Kids Definition

underground

1 of 3 adverb
un·​der·​ground ˌən-dər-ˈgrau̇nd How to pronounce underground (audio)
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 How to pronounce underground (audio)
1
: being, growing, operating, or located below the surface of the ground
an underground stream
2
: conducted secretly

More from Merriam-Webster on underground

Last Updated: - Updated example sentences
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