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
Relevance
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
as in resistance
a secret organization in a conquered country fighting against enemy forces
joined the underground while still a teenager
Synonyms & Similar Words
as in undercover
Related Words
Dissimilar Words
Example Sentences
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Recent Examples of underground
Adeola Adeosun, MSNBC Newsweek, 22 June 2025
The facility is burrowed so deep underground that only bunker-busting Massive Ordnance Penetrator bombs, which the United States has but Israel does not, could destroy the facility.
—Ilan Goldenberg, Foreign Affairs, 22 June 2025
Deborah Danan, Sun Sentinel, 26 June 2025
The Robust Nuclear Earth Penetrator, as the concept was known, would deliver a powerful shock to underground tunnels and bunkers.
—Geoff Brumfiel, NPR, 25 June 2025
Emily Palmer Heller, Vulture, 2 June 2025
The film’s synopsis reads: Set in London’s iconic shadowy underground, the malevolent figure of Creep unleashes fresh terror on unsuspecting tube passengers and Londoners.
—Andreas Wiseman, Deadline, 27 May 2025
See All Example Sentences for underground
Adjective
The Fordow facility, considered ground zero of Iran's nuclear program, is built deep underground near the holy city of Qom and has been enriching uranium to 60 percent purity, approaching weapons-grade levels.
—Adeola Adeosun, MSNBC Newsweek, 22 June 2025
The facility is burrowed so deep underground that only bunker-busting Massive Ordnance Penetrator bombs, which the United States has but Israel does not, could destroy the facility.
—Ilan Goldenberg, Foreign Affairs, 22 June 2025
Noun
At Haifa’s Rambam Health Care Campus — home to the world’s largest underground fortified hospital — patients and staff relocated below ground to continue round-the-clock care.
—Deborah Danan, Sun Sentinel, 26 June 2025
The Robust Nuclear Earth Penetrator, as the concept was known, would deliver a powerful shock to underground tunnels and bunkers.
—Geoff Brumfiel, NPR, 25 June 2025
Adverb
And that song is just this crazy underground hit with all those guys.
—Emily Palmer Heller, Vulture, 2 June 2025
The film’s synopsis reads: Set in London’s iconic shadowy underground, the malevolent figure of Creep unleashes fresh terror on unsuspecting tube passengers and Londoners.
—Andreas Wiseman, Deadline, 27 May 2025
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
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American veterans and others have traveled to smaller, clandestine clinics for treatment to deal with depression, post-traumatic stress disorder and addiction.—
Eduardo Cuevas,
USA Today,
29 June 2025
-
Gi-hun, who’d found his way back in the clandestine gaming complex (situated inside a mountain on a remote island), is Player 456 again among a new round of contestants.—
Lorraine Ali,
Los Angeles Times,
28 June 2025
Adjective
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For any subterranean tourist ready to explore the layers beneath the surface, this is where the adventure begins.—
Joseph V Micallef,
Forbes.com,
28 June 2025
-
In addition to precipitation, the Ayuk stream is also fed, in part, by subterranean streams.—
Lauren Liebhaber,
Miami Herald,
26 June 2025
Noun
-
Under these circumstances, the sole measure is the legitimacy of resistance itself.—
Beth Bailey,
FOXNews.com,
25 June 2025
-
If the Senate declines to act, the administration must release the funds—but bipartisan resistance suggests the plan could face major hurdles.—
Amanda Castro
Hannah Parry,
MSNBC Newsweek,
25 June 2025
Adjective
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On June 24, undercover agents attempted to purchase fireworks from Pan.—
Roni Jacobson,
New York Daily News,
30 June 2025
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Conan Edogawa and Detective Kogoro Mouri join the Nagano prefectural police to investigate a break-in at the observatory while uncovering a deeper plot involving undercover agents, betrayal, and vengeance.—
Naman Ramachandran,
Variety,
30 June 2025
Adjective
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Now, after Operation Midnight Hammer, arguably one of the most perfect covert military operations in U.S. history, who could argue? Even Trump’s most ardent critics had to give him credit.—
Sun Sentinel Editorial Board,
Sun Sentinel,
28 June 2025
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This deliberately allusive narrative style enables the author to elude the topic of Nazism—or at least to hint at it in a covert way, thus making the novel acceptable to a wide German audience at the time of its publication in 1968.—
Ombline Damy,
JSTOR Daily,
26 June 2025
Adjective
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Robyn and John Horn of Little Rock have donated 105 works of art from their private collection to the Arkansas Museum of Fine Arts, the art center’s executive director announced Monday.—
Arkansas Online,
Arkansas Online,
30 June 2025
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The Financial Times reported last week that Meta is seeking $29 billion from private capital firms for its all-in push to build AI data centers.—
Sharon Goldman,
Fortune,
30 June 2025
Cite this Entry
“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 5 Jul. 2025.
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