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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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
The demand has grown so high that an underground gray market has flourished in delivering those cult-classic burgers to hungry customers. — Tatiana Sataua, Fortune, 21 Oct. 2026 However, the macro networks our industry has engineered outdoors were never designed to penetrate deep underground or dense interiors. — Stephen Farrugia, Forbes.com, 20 Oct. 2026
Noun
The satellites chase each other in orbit to measure gravitational shifts in water mass, both on land and underground. — Ian James, Los Angeles Times, 24 Sep. 2026 Since the late 1990s, taxpayers have been funding a program to stash extra Colorado River water underground, with the idea that it could be used as a backup in times of shortage. — Alex Hager, NPR, 31 Aug. 2026
Adverb
Slickwater uses a mix of water, sand, and thin, friction-reducing chemicals rather than thicker gels to shatter dense shale rock deep underground and free the gas. — Jordan Blum, Fortune, 10 Oct. 2026 Think about how trees communicate with each other through their network of roots underground. — Clare Marie Schneider, NPR, 10 Oct. 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
  • The arrest, the official explained, came after the Attorney General’s Office concluded that there had been misconduct in an April operation in which state officials dismantled a clandestine drug-manufacturing laboratory.
    — Mauricio Torres, CNN Money, 18 Oct. 2026
  • Bridgers’ tour restricts phones, so the reader’s account had to stand in for the clandestine photo that might otherwise have accompanied the sighting.
    — Jeff Ihaza, Rolling Stone, 6 Oct. 2026
Definition of clandestine
Adjective
  • This infrastructure combines an above-ground encapsulation plant with a subterranean repository, known as Onkalo.
    — Mrigakshi Dixit, Interesting Engineering, 23 Oct. 2026
  • Prada Galleria now includes a new subterranean passage under the landmarked 19th-century shopping arcade that connects the women’s store with the men’s one, linking two sides of the central octagon.
    — Luisa Zargani, Footwear News, 22 Oct. 2026
Definition of subterranean
Noun
  • By understanding how these products evolve and diversify in bacteria, scientists might be able to tackle current resistance that humans have developed to some of the antibiotics that exist.
    — Maria Mocerino, Interesting Engineering, 24 Oct. 2026
  • In the hills surrounding Taiz, the government forces are trying to repel the Houthis but face stiff resistance, especially east of the city.
    — ABC News, ABC News, 24 Oct. 2026
Definition of resistance
Adverb
  • There had been small tweaks season to season as the series traveled to different locations — all of them telegraphed in the start-of-production slate photos that stealthily revealed the new logo (including the Season 4 one).
    — Nellie Andreeva, Deadline, 13 Oct. 2026
  • 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
Definition of stealthily
Adjective
  • But his father, also named William, became a supporter — and even went undercover of sorts at her 2021 fraud trial.
    — Los Angeles Times, Los Angeles Times, 20 Oct. 2026
  • The federal indictment identifies instructions directing undercover Cuban spies not to fly with Brothers to the Rescue around the time of the attack.
    — Antonio María Delgado, Miami Herald, 19 Oct. 2026
Definition of undercover
Adverb
  • The centerpiece of the government’s case is that the defendants surreptitiously drugged women.
    — Kara Scannell, CNN Money, 25 Oct. 2026
  • For years, scammers would surreptitiously install skimming devices on card readers at ATMs, gas pumps and corner stores.
    — Eli Hager, ProPublica, 13 Oct. 2026
Definition of surreptitiously
Adjective
  • But how and through whom the money flowed into the Alpha account revealed that it was intended to remain secret, more akin to a covert and illicit scheme, given that it was managed in part by a senior advisor to the president of the United States.
    — Matthew Cole, Vanity Fair, 22 Oct. 2026
  • Even in scenes outside Sonny’s perspective, Ellen still looks like not-quite-Connie Britton, fielding suspicious phone calls and making covert trips to the bank.
    — Alison Herman, Variety, 20 Oct. 2026
Definition of covert
Adverb
  • In 1983, Baker and Casey became embroiled in a public dispute over who had clandestinely obtained Jimmy Carter’s briefing book for the 1980 Presidential debate.
    — Bob Woodward, New Yorker, 19 Oct. 2026
  • 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
Definition of clandestinely

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Cite this Entry

“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 27 Oct. 2026.

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