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
Noah Lyons, San Diego Union-Tribune, 20 Mar. 2026
Building new data centers underground costs more than $2,000 per square foot in the US, Semafor’s Rachyl Jones reported.
—Kelsey Warner, semafor.com, 19 Mar. 2026
Cami Koons, Iowa Capital Dispatch, 17 Feb. 2026
Montreal’s underground is the RÉSO.
—Vivian Song, CNN Money, 17 Feb. 2026
Tiffany Acosta, AZCentral.com, 19 Mar. 2026
But the real recovery happens underground.
—The Editors, Outside, 18 Mar. 2026
See All Example Sentences for underground
Adjective
Concerned with drainage issues and potential safety hazards at Roseland and Spindrift drives, La Jollan Kurt Hoffman got the La Jolla Shores Association’s support for several proposals March 18 for possible additions to an ongoing project for underground utility lines.
—Noah Lyons, San Diego Union-Tribune, 20 Mar. 2026
Building new data centers underground costs more than $2,000 per square foot in the US, Semafor’s Rachyl Jones reported.
—Kelsey Warner, semafor.com, 19 Mar. 2026
Noun
While the concept of finding naturally occurring stores of hydrogen underground is relatively new, Johnson said the process of drilling and producing hydrogen wells is well established science and uses the same rigs used to drill for natural gas.
—Cami Koons, Iowa Capital Dispatch, 17 Feb. 2026
Montreal’s underground is the RÉSO.
—Vivian Song, CNN Money, 17 Feb. 2026
Adverb
Exploring underground at Kartchner Caverns State Park provides a naturally cool, sun-free environment.
—Tiffany Acosta, AZCentral.com, 19 Mar. 2026
But the real recovery happens underground.
—The Editors, Outside, 18 Mar. 2026
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
-
The Pozo de Vargas is considered the largest clandestine mass grave of Argentina’s last dictatorship with the remains of 149 people recovered from the site.—
Débora Rey,
Los Angeles Times,
24 Mar. 2026
-
The Pozo de Vargas is considered the largest clandestine mass grave of Argentina’s last dictatorship with the remains of 149 people recovered from the site.—
ABC News,
ABC News,
22 Mar. 2026
Adjective
-
Giant subterranean sandworms measuring 1,500 feet long; a narcotic that fuels interstellar travel and bends a user’s perception of space-time; a mystical cabal of eugenicist witches—the list goes on.—
Andrew Paul,
Popular Science,
19 Mar. 2026
-
Accessed via a brick staircase in the garden, the subterranean passages run beneath the house and grounds, forming a series of chambers carved out centuries ago as part of a sand mine.—
Abby Montanez,
Robb Report,
17 Mar. 2026
Noun
-
For those living in fire country, fire resistance has become a must-have in new builds.—
Tori Latham,
Robb Report,
20 Mar. 2026
-
Fleming was found hiding under a rock on a remote ridge and taken into custody without resistance, according to the outlet.—
Michael Sinkewicz,
FOXNews.com,
20 Mar. 2026
Adjective
-
Law enforcement officials said the officer was ambushed by two gunmen and shot while driving an unmarked white Tesla while working on an undercover investigation.—
Washington Examiner Staff,
The Washington Examiner,
24 Mar. 2026
-
Owners cited undercover consumers known to visit establishments in search of those airing content without licenses.—
Jacob Feldman,
Sportico.com,
23 Mar. 2026
Adverb
-
Such cerebral, stealthily political dramas have made Petzold an auteur’s auteur, beloved by the likes of Claire Denis and Brady Corbet.—
Holden Seidlitz,
New Yorker,
20 Mar. 2026
-
But the major platform of the Oscars also brings another level of exposition, which is not always beneficial for a documentary director trying to move stealthily and precisely.—
Rafa Sales Ross,
Variety,
20 Mar. 2026
Adjective
-
These shows join the likes of Conspiracies and Coverups, hosted by former CIA covert agent Andrew Bustamante, which launches on April 1, and Jeff Dunham’s The Cars That Drove Us, which premieres on March 31.—
Peter White,
Deadline,
20 Mar. 2026
-
The Department of the Treasury last Thursday designated Hayat Yolu as a key player in a covert global network that uses the guise of humanitarian aid to raise money overseas.—
Bonny Chu,
FOXNews.com,
20 Mar. 2026
Adverb
-
Maritime tracking firm Winward suggested the ship may have spoofed its location and surreptitiously delivered the fuel to Cuba already.—
Nora Gámez Torres,
Miami Herald,
20 Mar. 2026
-
Slipping surreptitiously from documentary to drama, the story of Junyi, a Catalan of Chinese decent, and his embrace of his roots, moved by the singular draw of family history, and with that a multi-cultural identity.—
Ed Meza,
Variety,
10 Mar. 2026
Adjective
-
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 27 Mar. 2026.
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