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
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
Synonyms & Similar Words
Antonyms & Near Antonyms
Example Sentences
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Recent Examples of underground
Nellie Andreeva, Deadline, 17 Apr. 2025
Early in this episode, Dina mentions to a preoccupied Joel that one of the community’s underground pipes — connected to the outside — has been rendered useless by encroaching roots.
—Noel Murray, New York Times, 14 Apr. 2025
Bychristie Wilcox, science.org, 8 Jan. 2025
Salt water from the ocean or underground is rich in minerals and may provide the body with magnesium.
—Susan Bard, Health, 18 Mar. 2025
Scott Roxborough, HollywoodReporter, 7 Apr. 2025
Do this: Explore the Bluff View Art District, head underground at Raccoon Mountain Caverns and hike Lookout Mountain's Guild-Hardy Trail.
—Thomas Wheatley, Axios, 28 Mar. 2025
See All Example Sentences for underground
Adjective
So the impressive stunt was overshadowed by Station 118 Captain Bobby Nash (Krause) dying just minutes later at an underground lab where a fire had triggered the release of a deadly virus.
—Nellie Andreeva, Deadline, 17 Apr. 2025
Early in this episode, Dina mentions to a preoccupied Joel that one of the community’s underground pipes — connected to the outside — has been rendered useless by encroaching roots.
—Noel Murray, New York Times, 14 Apr. 2025
Noun
Yet their biology and diversity are poorly understood because of the inherent difficulty in studying species that live their whole lives up to a meter and a half underground.
—Bychristie Wilcox, science.org, 8 Jan. 2025
Salt water from the ocean or underground is rich in minerals and may provide the body with magnesium.
—Susan Bard, Health, 18 Mar. 2025
Adverb
As the temperature rises underground, this highly contagious and rapidly mutating microorganism multiplies and unleashes its brain-controlling, body-bursting terrors on the facility’s inhabitants – human and otherwise.
—Scott Roxborough, HollywoodReporter, 7 Apr. 2025
Do this: Explore the Bluff View Art District, head underground at Raccoon Mountain Caverns and hike Lookout Mountain's Guild-Hardy Trail.
—Thomas Wheatley, Axios, 28 Mar. 2025
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
-
After authorities responded with mass arrests, weavers formed clandestine committees and took secret oaths.—
John Cassidy,
New Yorker,
14 Apr. 2025
-
Til Schweiger plays a sardonic whale-tourism boat captain (and former elite military operative, obviously) who gets roped into taking down a clandestine organization that’s building the perfect super-soldier through genetic experiments.—
Jordan Crucchiola,
Vulture,
4 Apr. 2025
Adjective
-
Found in a water tank, this new species lives underground and might still be evolving towards a fully subterranean life.—
Stories by Real-Time news team, with AI summarization,
Miami Herald,
18 Apr. 2025
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An entire subterranean floor dedicated to wellness has been carved out to create the largest spa area of any hotel in the city, while the 126 rooms and suites have a classic contemporary feel, with bespoke Belgian artwork hanging on the wall.—
Travel + Leisure Editors,
Travel + Leisure,
16 Apr. 2025
Noun
-
Chromium uses chemicals to preserve the animal's skin, and offers more water and heat resistance for the leather products it's applied to.—
Gia Yetikyel,
Vogue,
26 Apr. 2025
-
The Shin Bet chief’s sudden status as a hero of resistance to Netanyahu is pregnant with irony.—
Gershom Gorenberg,
The Atlantic,
25 Apr. 2025
Adjective
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Former Attorney General Merrick Garland said in October that the Justice Department foiled the plot as the men bought the rifles from an undercover FBI employee.—
Krystal Nurse,
USA Today,
18 Apr. 2025
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Kasie discovers that the Poet used jeweler Gemma Wood (Michelle Lukes) as a go-between to broker deals with anonymous clients, so Torres goes undercover as the man himself since news of his death hasn't left NCIS HQ.—
Sara Netzley,
EW.com,
15 Apr. 2025
Adjective
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After the unexpected death of the pope, Cardinal Lawrence (Ralph Fiennes) is tasked with running the covert process of choosing a new leader.—
Saman Shafiq,
USA Today,
22 Apr. 2025
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Those documents gave curious readers more details about Cold War-era covert U.S. operations in other nations, but did not initially lend credence to long-circulating conspiracy theories about who killed JFK.—
Josh Funk and Haya Panjwani,
Los Angeles Times,
18 Apr. 2025
Adjective
-
In 2022, a consortium of private retirement-plan providers announced a collaboration to boost the portability of small retirement accounts.—
Daniel de Visé,
USA Today,
20 Apr. 2025
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The firm’s team includes analysts from leading tech private equity firms, engineers, operating partners – former technology CEOs and COOs.—
Kenneth Squire,
CNBC,
19 Apr. 2025
Cite this Entry
“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 30 Apr. 2025.
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