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
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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
Jon Gambrell, Los Angeles Times, 15 Jan. 2025
On behalf of millions of riders, thank you Guv for making underground safety such a priority.
—New York Daily News Editorial Board, New York Daily News, 15 Jan. 2025
Kate O'Flaherty, Forbes, 11 Sep. 2024
An Enbridge Energy pipeline in Jefferson County spilled nearly 70,000 gallons of crude oil underground, according to federal officials.
—Drake Bentley, Journal Sentinel, 13 Dec. 2024
Rafael Peña, Miami Herald, 10 Jan. 2025
Most of the trenches had already been filled, and over the next week or so, if the weather held, the rest would be put back underground.
—Peter Ross, Smithsonian Magazine, 8 Jan. 2025
See all Example Sentences for underground 
Adjective
In April 2021, another blast tore apart one of its underground enrichment halls.
—Jon Gambrell, Los Angeles Times, 15 Jan. 2025
On behalf of millions of riders, thank you Guv for making underground safety such a priority.
—New York Daily News Editorial Board, New York Daily News, 15 Jan. 2025
Noun
Fraudsters can access your personal details — such as your name and email address — and sell them on the criminal underground known as the dark web.
—Kate O'Flaherty, Forbes, 11 Sep. 2024
An Enbridge Energy pipeline in Jefferson County spilled nearly 70,000 gallons of crude oil underground, according to federal officials.
—Drake Bentley, Journal Sentinel, 13 Dec. 2024
Adverb
Located 145 feet underground, this natural wonder is a geological masterpiece.
—Rafael Peña, Miami Herald, 10 Jan. 2025
Most of the trenches had already been filled, and over the next week or so, if the weather held, the rest would be put back underground.
—Peter Ross, Smithsonian Magazine, 8 Jan. 2025
See all Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
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Given the clandestine nature of the process, the true number of fictitious sons who arrived during exclusion will never be known.—
Jane Hu,
The New Yorker,
23 Jan. 2025
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Inspired by the Belle Époque era in 1900 Buenos Aires, the soaring space manages to feel clandestine with its dim lighting, lush floral displays, and bartenders in crisp white jackets.—
Lauren Mowery,
Forbes,
22 Jan. 2025
Adjective
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Photo : Carmel Realty Company The castle-like Turret House comes with a stainless spiral staircase leading down to a subterranean garage.—
Wendy Bowman,
Robb Report,
24 Jan. 2025
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The tunnels were discovered by experts from the Polytechnic University of Milan, who used ground-penetrating radar and laser scanners to map the 15th-century stronghold’s subterranean structures.—
Sonja Anderson,
Smithsonian Magazine,
24 Jan. 2025
Noun
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SpaceX is developing the Starship system, which could provide a reusable alternative, but moves to cancel SLS — which has been criticized over unsustainable costs and numerous delays and quality control on the part of lead contractor Boeing — will likely face resistance.—
Andrew Jones,
Space.com,
20 Jan. 2025
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United States Oil Fund (NYSE: USO) Price in January established a new high after breaking above the early July resistance area.—
John Navin,
Forbes,
20 Jan. 2025
Adjective
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One that, again, merged something familiar – an undercover cop – with something unfamiliar: the world of art fraud.—
Marta Balaga,
Variety,
24 Jan. 2025
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In 2023, Benjamin Coney, 30, and Emily Grace Brinley, 26, both from Conway, messaged an undercover FBI agent posing as a mom of two girls, according to a Jan. 16 news release by the U.S. Attorney’s Office for the Western District of Arkansas.—
Paloma Chavez,
Kansas City Star,
21 Jan. 2025
Adjective
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This isn’t a sly spy carrying out a covert operation; this is a spy whose careful plans have been overtaken by events.—
Ben Travers,
IndieWire,
24 Jan. 2025
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The Jacksonville Jaguars hired Tampa Bay Buccaneers offensive coordinator Liam Coen as the eighth head coach in franchise history Friday, capping a covert operation that included owner Shad Khan moving on from general manager Trent Baalke and Coen reversing course with the Bucs.—
Mark Long,
Chicago Tribune,
24 Jan. 2025
Adjective
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The race drivers are limited to 1,000km of private test running in old cars through the year, meaning Hamilton’s 89km run, followed by teammate Charles Leclerc’s 42km run in the afternoon, leaves plenty of room for more ahead of the new season.—
Luke Smith,
The Athletic,
25 Jan. 2025
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The billionaire declined to share details on his sources of financing, but said private equity firms and family offices have reached out to provide options.—
Krystal Hu,
USA TODAY,
25 Jan. 2025
Thesaurus Entries Near underground
Cite this Entry
“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 1 Feb. 2025.
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