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
Todd Karpovich, Baltimore Sun, 13 Feb. 2026
Demand for the minerals needed for everything from smartphones to computer chips and batteries is sky high, but mining has always struggled with uncertainty about the true nature of underground discoveries.
—Alexis Akwagyiram, semafor.com, 13 Feb. 2026
Alphonse Pierre, Pitchfork, 30 Jan. 2026
The beauty of a fire underground is that heat rises.
—Literary Hub, 16 Jan. 2026
Aman Tripathi, Interesting Engineering, 11 Feb. 2026
With the help of the architecture firm Gensler and the design company Blueprint Studios, Live Nation is studying the possibility of inserting a second large, but more manageable, 5,000-person venue underground.
—Justin Davidson, Curbed, 10 Feb. 2026
See All Example Sentences for underground
Adjective
More than a year after an underground fire shut down part of Charles Street near Mount Vernon, nearby businesses say the disruption continues to hurt foot traffic and deliveries.
—Todd Karpovich, Baltimore Sun, 13 Feb. 2026
Demand for the minerals needed for everything from smartphones to computer chips and batteries is sky high, but mining has always struggled with uncertainty about the true nature of underground discoveries.
—Alexis Akwagyiram, semafor.com, 13 Feb. 2026
Noun
Pres, a veteran of the East Coast underground, became familiar with Gabe after hearing him rip a verse on billy woods’ 2022 album, Aethiopes.
—Alphonse Pierre, Pitchfork, 30 Jan. 2026
The beauty of a fire underground is that heat rises.
—Literary Hub, 16 Jan. 2026
Adverb
This method uses directional drilling technology to place waste hundreds of meters underground within stable geological formations rather than excavating large tunnels in a mine.
—Aman Tripathi, Interesting Engineering, 11 Feb. 2026
With the help of the architecture firm Gensler and the design company Blueprint Studios, Live Nation is studying the possibility of inserting a second large, but more manageable, 5,000-person venue underground.
—Justin Davidson, Curbed, 10 Feb. 2026
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
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Treasury also sanctioned associates, companies and vessels allegedly involved in a network used by Maduro’s former oil minister, Tareck El Aissami, to evade sanctions and resell Venezuelan crude through clandestine channels.—
Antonio María Delgado,
Miami Herald,
17 Feb. 2026
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Earlier this month, state officials reported dismantling a clandestine drug laboratory located south of Ensenada, marking the ninth such laboratory shut down by authorities in the span of a year.—
Alexandra Mendoza,
San Diego Union-Tribune,
15 Feb. 2026
Adjective
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Here are two more stories of the subterranean, one sinister and one salty.—
Maureen O'Hare,
CNN Money,
21 Feb. 2026
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Their translucent bodies suggest adaptation to a subterranean environment where light doesn’t reach.—
Hanna Wickes,
Miami Herald,
20 Feb. 2026
Noun
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The work focuses on dysprosium, a heavy rare-earth element used to improve heat resistance in magnets and stabilize nuclear control rods.—
Neetika Walter,
Interesting Engineering,
20 Feb. 2026
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In the lab, the researchers isolated various bacterial strains and sequenced their genomes to evaluate which genes allow the strain to survive in low temperatures and which are linked to antimicrobial resistance.—
Katie Hunt,
CNN Money,
20 Feb. 2026
Adjective
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Based on a 2019 Cosmopolitan article, the limited series follows an undercover investigator, played by Chastain, who infiltrates domestic extremist groups to thwart catastrophic large-scale attacks.—
Cheyenne Roundtree,
Rolling Stone,
15 Feb. 2026
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The measure would allow some exemptions, including for officers involved in undercover operations and SWAT duties or who are wearing religious garb.—
Elliott Wenzler,
Denver Post,
11 Feb. 2026
Adverb
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Mostly, however, Gee’s sophisticated, stealthily moving film folds any bursts of emotion into its exquisitely dark shadows, letting Evans’ limpid but heartsore music do most of the weeping.—
Guy Lodge,
Variety,
13 Feb. 2026
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Under the noses of her family, Kelly’s business team, and the revolving door of yes-people in his recording studio and homes, the book details how Kelly stealthily groomed the middle-schooler in plain sight.—
Cheyenne Roundtree,
Rolling Stone,
31 Jan. 2026
Adjective
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The historic Vietnamese revolutionary Ho Chi Minh is said to have used the hotel as a covert meeting spot during the First Indochina War.—
Sofia Celeste,
Footwear News,
14 Feb. 2026
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What else is going on A Southern California man was sentenced to four years in prison for acting as a covert Chinese agent while helping elect an Arcadia City Council member.—
James Rainey,
Los Angeles Times,
11 Feb. 2026
Adverb
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Callella, 42, is accused of using a voice over internet protocol text and call application to surreptitiously reach out to the family, but authorities were able to link the phone number to his email address and, later, his residence, according to the complaint.—
Richard Winton,
Los Angeles Times,
6 Feb. 2026
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Fox said the exchange between him and Wasser when he was called back to the restaurant took about 10-12 seconds, but defense attorney Karen Friedman Agnifilo suggested on Monday that the pair may have surreptitiously searched the backpack at that time and found the gun — or potentially planted it.—
Ben Brachfeld,
PEOPLE,
9 Dec. 2025
Adjective
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Get Ready: Katy Perry Has Released a Sneak Peek of Her New Song And the internet has receipts.—
Mehera Bonner,
Marie Claire,
15 Mar. 2017
Cite this Entry
“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 21 Feb. 2026.
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