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
Luisa Zargani, Footwear News, 19 June 2026
Install underground fencing and remove food sources to keep pests out.
—Abby Monteil, The Spruce, 19 June 2026
Joe Yogerst, Forbes.com, 28 May 2026
When oil wells are shut in, the pressure underground can become imbalanced, deforming the underlying structure.
—David Goldman, CNN Money, 27 May 2026
Noah Daly, Idaho Statesman, 11 June 2026
The president's comment may leave room for Iran to keep its enriched uranium that's buried underground.
—Mark Osborne, CBS News, 11 June 2026
See All Example Sentences for underground
Adjective
The women’s store will be expanded, and the two units will be linked by a new underground passage.
—Luisa Zargani, Footwear News, 19 June 2026
Install underground fencing and remove food sources to keep pests out.
—Abby Monteil, The Spruce, 19 June 2026
Noun
Visitors help the staff dig and build a traditional imu underground with volcanic rocks, banana stumps, ti leaves and burlap sacks, and then fill the pit with mea ʻai staples like kālua pork, chicken, taro, yams and breadfruit.
—Joe Yogerst, Forbes.com, 28 May 2026
When oil wells are shut in, the pressure underground can become imbalanced, deforming the underlying structure.
—David Goldman, CNN Money, 27 May 2026
Adverb
The first phase includes grading the site, building roadways around the property, constructing ball fields and relocating existing overhead power lines underground, the latter of which has already been completed in a contract with Idaho Power.
—Noah Daly, Idaho Statesman, 11 June 2026
The president's comment may leave room for Iran to keep its enriched uranium that's buried underground.
—Mark Osborne, CBS News, 11 June 2026
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
-
Some may be announced publicly; others may happen in more clandestine ways.—
Eben Novy-Williams,
Sportico.com,
10 June 2026
-
But clandestine flows aren’t the biggest factor behind the market calm.—
Matt Egan,
CNN Money,
9 June 2026
Adjective
-
Then comes the subterranean twist.—
Mrigakshi Dixit,
Interesting Engineering,
17 June 2026
-
Be sure to hit the subterranean SoWa Vintage Market for thrifting finds, and on weekends from spring through fall the outdoor SoWa Open Market sets up shop with local vendors, artisans, food purveyors, farmers, and food and drink trucks selling their wares in a fun, alfresco setting.—
Shannon McMahon,
Condé Nast Traveler,
17 June 2026
Noun
-
There’s a dry, droll seam of generation-gap humor in George’s continued, failed attempts to insert himself as a father figure into the life of someone who never asked for one, and Zeke’s blankly bemused resistance to his efforts.—
Guy Lodge,
Variety,
19 June 2026
-
The plan to buy large warehouses unfit for human habitation and spend millions more to convert them to prisons sparked nationwide backlash and pointed resistance in Social Circle and Oakwood.—
AJ Willingham,
AJC.com,
19 June 2026
Adverb
-
It’s largely escaped detection outside the 617 area code, but NESN has stealthily developed arguably the most homegrown MLB crew on TV, so much so that just about everyone who covers the Sox was brought up within a 150-mile radius of Fenway Park.—
Anthony Crupi,
Sportico.com,
12 June 2026
-
The building is stealthily spacious with 40 bedrooms, and there’s a serious Sisley spa, designed with monkish minimalism, plus four superb restaurants.—
Matt Ortile,
Condé Nast Traveler,
3 June 2026
Adjective
-
In 2005, an undercover investigator from the FDA called the farm and was told the milk was safe for human consumption.—
CNN Money,
CNN Money,
14 June 2026
-
Following a months-long undercover operation, in which a female officer posed as a romantic interest to extract information, Stagg was taken into custody, per The Guardian.—
Emily Blackwood,
PEOPLE,
13 June 2026
Adverb
-
As a group of dancers surrounded her on the B-stage, she was surreptitiously harnessed into a rig that carried her aloft, limp yet belting, into the heavens, or at least into what looked like a UFO hovering over the arena.—
Chris Willman,
Variety,
7 June 2026
-
Gray-hat hackers, unlike white-hats, surreptitiously sneak into corporate systems to find security vulnerabilities.—
Winston Cho,
HollywoodReporter,
4 June 2026
Adjective
-
The film follows cybersecurity expert Daniel Kellner (Josh O’Connor), who lifts secret files about the existence of aliens from Wardex, a covert non-government organization that used to employ him.—
Tim Lammers,
Forbes.com,
13 June 2026
-
The investigation also linked the activity to China based on IP addresses associated with a LinkedIn account and a Gmail account tied to the covert recruitment scheme.—
Michael Kan,
PC Magazine,
10 June 2026
Adverb
-
This great disparity between reality and story, truth and history, takes on new dimensions when Robin clandestinely takes refuge at an island priory where Sister Brigid (Jodie Comer) tends to his wounds.—
ABC News,
ABC News,
17 June 2026
-
Other examples of politically motivated pirate radio can be found around the world, some of them clandestinely backed by governmental intelligence agencies, but many of them existing as truly grassroots endeavors.—
Encyclopedia Britannica,
Encyclopedia Britannica,
23 Apr. 2026
Cite this Entry
“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 21 Jun. 2026.
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