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

Synonyms & Similar Words

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
Although the convent was demolished in the 16th century and hundreds of thousands of its bricks were removed, much of its underground footprint survived. — Andrea Margolis, FOXNews.com, 7 Sep. 2026 In the driller's cabin atop the rig, screens display real-time metrics sent back from underground sensors — data that's simultaneously being monitored from company headquarters in Houston. — Pippa Stevens, CNBC, 5 Sep. 2026
Noun
To many, Anthony Bourdain is the patron saint of the culinary underground. — Patrick Ryan, USA Today, 13 Aug. 2026 The frustrations of manufacturing clean hydrogen have convinced many entrepreneurs and scientists to instead seek the element underground. — IEEE Spectrum, 11 Aug. 2026
Adverb
A certain amount of secrecy surrounds the White House worksite, in part because of a large military structure that is being built underground, beneath where the ballroom will stand. — Janay Kingsberry, The Atlantic, 5 Sep. 2026 There are also military capabilities there, including air defenses and mines buried underground. — Gabrielle Khoriaty, NBC news, 5 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
  • Or that the Apollo moon landing in 1969 was staged, the video shot on some clandestine movie set.
    — Susan Page, USA Today, 1 Sep. 2026
  • The clandestine manner in which LG monitors were installing ad-pushing software onto third-party devices, however, remains seriously concerning.
    — Scharon Harding, ArsTechnica, 24 Aug. 2026
Definition of clandestine
Adjective
  • Scheduled for late 2026, Ceres will drill the world’s first commercial-scale superhot horizontal wells, bringing subterranean power one step closer to the grid.
    — Mrigakshi Dixit, Interesting Engineering, 4 Sep. 2026
  • The Den, a subterranean hangout just down the stairs, feels like the Platonic ideal of hanging out in your parents’ basement, with plenty of seating and a pool and backgammon table to play around on.
    — Condé Nast, Condé Nast Traveler, 2 Sep. 2026
Definition of subterranean
Noun
  • Aside from a matchup with Notre Dame in November, Miami won’t face a ton of resistance on its 2026 schedule (which will be a talking point on several levels over the next few months).
    — Dane Brugler, New York Times, 8 Sep. 2026
  • His persistent claims raised sovereignty concerns and caused resistance from Greenlandic and Danish leaders and heightened tensions among NATO allies.
    — Lorne Cook, Los Angeles Times, 7 Sep. 2026
Definition of resistance
Adverb
  • 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
  • From there, the group could stealthily disperse the new strain through air-handling systems at major livestock farms across the United States.
    — Elizabeth Sherwood-Randall, Foreign Affairs, 18 Aug. 2026
Definition of stealthily
Adjective
  • And in 1963, Steinem gained national attention for going undercover at one of Hugh Hefner's nightclubs.
    — Juliana Kim, NPR, 3 Sep. 2026
  • The rest of the officers at the Pinellas County Sheriff's Office who were part of setting this undercover operation up and didn’t listen owe the officer an apology.
    — Sean Joseph OutKick, FOXNews.com, 2 Sep. 2026
Definition of undercover
Adverb
  • In June, Wilder resident Tyler Cain filed a tort claim against the city, alleging the city’s three Flock Safety cameras were acquired surreptitiously and outside the measure of the law.
    — Noah Daly September 2, Idaho Statesman, 2 Sep. 2026
  • These malicious apps can be surreptitiously installed by remote attackers even when the devices are positioned behind a router.
    — Dan Goodin, ArsTechnica, 31 Aug. 2026
Definition of surreptitiously
Adjective
  • Over the last decade, covert tests have revealed vulnerabilities at security checkpoints, with one in 2015 showing a nearly 96% failure rate at screening fake explosives.
    — Kathleen Wong, USA Today, 3 Sep. 2026
  • The film imagines a colorful, family-friendly realm concealed just under the surface of video games themselves, populated by a covert guild of guardians tasked with keeping each title operating and preserving every player’s journey.
    — Naman Ramachandran, Variety, 1 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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Cite this Entry

“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 11 Sep. 2026.

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Britannica.com: Encyclopedia article about underground

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