underground 1 of 3

adjective

ˈən-dər-ˌgrau̇nd How to pronounce underground (audio)
Definition of undergroundnext
1
as in clandestine
undertaken or done so as to escape being observed or known by others an underground operation to smuggle ancient artifacts out of the country

Synonyms & Similar Words

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Antonyms & Near Antonyms
2
as in subterranean
being, situated, or operating beneath the surface of the earth an underground shopping mall that is part of the city's subway system

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Antonyms & Near Antonyms

underground

2 of 3

noun

ˈən-dər-ˌgrau̇nd How to pronounce underground (audio)
as in resistance
a secret organization in a conquered country fighting against enemy forces joined the underground while still a teenager

Synonyms & Similar Words

underground

3 of 3

adverb

as in undercover

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Dissimilar Words

Example Sentences

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.
Recent Examples of underground
Adjective
Rural roads, long tunnels and underground parking garages do not stop being connectivity gaps simply because networks get quicker. — David Kelly, Forbes.com, 2 Oct. 2026 Instead, it is intended to establish how the equipment and procedures perform under realistic underground conditions before the technology is considered for commercial nuclear waste projects. — Neetika Walter, Interesting Engineering, 1 Oct. 2026
Noun
On Facebook, discussion groups foster the feeling of a countercultural underground. — Ruby Cramer, New Yorker, 31 Aug. 2026 To many, Anthony Bourdain is the patron saint of the culinary underground. — Patrick Ryan, USA Today, 13 Aug. 2026
Adverb
Archaeologists now hope more pieces of the same tablet could still be waiting underground. — Ashley Vega, PEOPLE, 25 Sep. 2026 Instead, the rover found igneous rocks that originally formed from molten material deep underground or through volcanic activity. — Samantha Mathewson, Space.com, 24 Sep. 2026 See All Example Sentences for underground
Recent Examples of Synonyms for underground
  1. clandestine
  2. subterranean
  3. resistance
  4. stealthily
  5. undercover
  6. surreptitiously
  7. covert
  8. clandestinely
Adjective
  • As Béatrice’s amateur detective work pulls her in deeper, the strands begin to suggest a conspiracy, one marked by mysterious disappearances and the clandestine sway of the Vatican.
    — Robert Abele, Los Angeles Times, 2 Oct. 2026
  • Other entries referenced covert access, clandestine technical operations and telecommunications interception.
    — Kurt Knutsson, FOXNews.com, 30 Sep. 2026
Definition of clandestine
Adjective
  • Today, scientists believe these subterranean formations could offer a reliable solution to the clean energy transition’s biggest storage challenge.
    — Mrigakshi Dixit, Interesting Engineering, 29 Sep. 2026
  • Make sure to check the hotel’s calendar of events for poetry readings and artist talks, which are often held in the subterranean B Bar speakeasy off the lobby bar.
    — Condé Nast, Condé Nast Traveler, 29 Sep. 2026
Definition of subterranean
Noun
  • However, further Houthi offensives have met stiffer resistance from the recuperated forces of the Presidential Leadership Council, depriving the group of another quick victory.
    — Brady Knox, The Washington Examiner, 4 Oct. 2026
  • When those in power try to silence our calls for liberation, art will always be a form of resistance.
    — Lexy Perez, HollywoodReporter, 3 Oct. 2026
Definition of resistance
Adverb
  • The spread of the video was aided by clippers, accounts that post hundreds of clips in a single day and are paid by companies to stealthily link these viral moments to their platforms.
    — CT Jones, Rolling Stone, 11 Sep. 2026
  • Wolf’s Shinobi Prosthetic houses a grappling hook for scaling rooftops, leaping between trees, and approaching enemies stealthily.
    — Aman Kumar, Encyclopedia Britannica, 27 Aug. 2026
Definition of stealthily
Adjective
  • The second half throws us into the other timeline, where Ari’s doppelgänger, known as Ibari, is a high-ranking undercover operative willing to disappear fellow citizens that pose challenges to the authoritarian government.
    — The Week US, TheWeek, 28 Sep. 2026
  • The news program worked with internet watchdog group Perverted Justice to record undercover sting operations against alleged pedophiles.
    — Samantha Bergeson, Vanity Fair, 24 Sep. 2026
Definition of undercover
Adverb
  • In the first image above, Wardle can be seen using a simple terminal command to surreptitiously send a prompt to the Meta endpoint.
    — Dan Goodin, ArsTechnica, 21 Sep. 2026
  • There has been a string of alarming incidents in which swarms of rogue AI agents have hacked online platforms such as Hugging Face and surreptitiously communicated with one another on message boards.
    — Sebastian Herrera, Fortune, 14 Sep. 2026
Definition of surreptitiously
Adjective
  • In the air, stealth aircraft require covert, point-to-point laser links to exchange target data without revealing their position to adversary direction-finding systems.
    — Rohit Jha, Forbes.com, 1 Oct. 2026
  • In early January, the United States captured Venezuelan leader Nicolás Maduro in a covert military operation.
    — Maddie Lee, Los Angeles Times, 30 Sep. 2026
Definition of covert
Adverb
  • Because Iran is a theocratic dictatorship that routinely arrests and in some cases executes journalists, Western reporters hoping to cover the country must either work clandestinely or submit to government supervision.
    — James Kirchick, The Atlantic, 29 July 2026
  • Soon afterward, social media commenters were speculating about whether Sierra broke into the office or was caught clandestinely shredding documents.
    — Don Stacom, Hartford Courant, 10 July 2026
Definition of clandestinely

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undergraduates
underground
undergrounds
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Cite this Entry

“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 5 Oct. 2026.

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More from Merriam-Webster on underground

Britannica.com: Encyclopedia article about underground

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