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
Matt Egan, CNN Money, 22 Jan. 2026
Metro’s board of directors unanimously approved an underground heavy-rail option Thursday that would go from Van Nuys to Sherman Oaks, pass under the mountains and Bel Air, stop at UCLA and ultimately end at the E Line/Expo Sepulveda station.
—Los Angeles Times, 22 Jan. 2026
Arricca Elin Sansone, Southern Living, 19 Dec. 2025
In its post-apocalyptic future, an AI fleet of drones and robots has forced humanity underground, but the origins of the robotic invaders are unknown.
—Fran Ruiz, Space.com, 10 Dec. 2025
Christopher Elliott, USA Today, 1 Jan. 2026
When millions of New Yorkers are counting down to 2026 on New Year's Eve, Mayor-elect Zohran Mamdani will be sworn in as the city's 111th mayor during a private ceremony underground.
—CBS News, 29 Dec. 2025
See All Example Sentences for underground
Adjective
Trump officials view Greenland’s underground riches as a way to loosen China’s stranglehold over the rare-earth metals that are critical for everything from fighter jets and lasers to electric vehicles and MRI scanners.
—Matt Egan, CNN Money, 22 Jan. 2026
Metro’s board of directors unanimously approved an underground heavy-rail option Thursday that would go from Van Nuys to Sherman Oaks, pass under the mountains and Bel Air, stop at UCLA and ultimately end at the E Line/Expo Sepulveda station.
—Los Angeles Times, 22 Jan. 2026
Noun
Leaf litter supports these insects by providing shelter and offering additional insulation for species that overwinter underground.
—Arricca Elin Sansone, Southern Living, 19 Dec. 2025
In its post-apocalyptic future, an AI fleet of drones and robots has forced humanity underground, but the origins of the robotic invaders are unknown.
—Fran Ruiz, Space.com, 10 Dec. 2025
Adverb
Next year, the focus is shifting underground.
—Christopher Elliott, USA Today, 1 Jan. 2026
When millions of New Yorkers are counting down to 2026 on New Year's Eve, Mayor-elect Zohran Mamdani will be sworn in as the city's 111th mayor during a private ceremony underground.
—CBS News, 29 Dec. 2025
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
-
Manned semisubmersibles built in clandestine jungle shipyards have been used for decades to ferry cocaine north from Colombia, the world's biggest cocaine producer, to Central America or Mexico.—
CBS News,
CBS News,
26 Jan. 2026
-
Written and directed by Jafar Panahi (known for his clandestine 2011 documentary This Is Not a Film), the story follows released political prisoners seeking revenge after a chance roadside meeting.—
Savannah Walsh,
Vanity Fair,
22 Jan. 2026
Adjective
-
Or, head downstairs in their wine-cellar-style dining space a late night subterranean drink.—
Jessica Chapel,
Condé Nast Traveler,
30 Jan. 2026
-
Sinclair is probably the most adept living navigator of London’s subterranean currents.—
Hari Kunzru,
Harpers Magazine,
27 Jan. 2026
Noun
-
And Republicans believe that some of the demands from Democrats go too far, signaling early resistance to a ban on the face masks agents wear to shield their identity.—
David Sivak,
The Washington Examiner,
31 Jan. 2026
-
Ruth Terry Walden teaches literature at Westhill High School, a public school in Stamford, and focuses her courses on themes of protest, resistance, and direct action.—
Literary Hub,
Literary Hub,
30 Jan. 2026
Adjective
-
According to the District Attorney’s Office, Akers was working undercover as part of a task force when Stewart, 46, ran from uniformed law enforcement officers and then hid inside an unlocked tow truck.—
Alex Riggins,
San Diego Union-Tribune,
26 Jan. 2026
-
The undercover investigators later spoke with Lorenz by phone.—
Rosalio Ahumada,
Sacbee.com,
24 Jan. 2026
Adverb
-
Some Gen Z have been desperately trying to break into the job market, sending out thousands of applications, standing on Wall Street with a sign begging for a job, and waitressing at industry conferences to stealthily hand out their resumes.—
Emma Burleigh,
Fortune,
9 Dec. 2025
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Two minutes later, while moving through the crowd, I was stealthily pickpocketed and spent hours the next day at the police station filing a theft report.—
Lane Nieset,
Travel + Leisure,
22 Nov. 2025
Adjective
-
Over the course of the novel, each Flynn girl is suspended from school at least once for some screwball infraction, including spreading conspiratorial theories about covert surveillance operations in town, punching another kid in the face, and preparing to commit an act of domestic terrorism.—
Hannah Gold,
New Yorker,
21 Jan. 2026
-
After Cruise's Ethan Hunt is falsely accused of planting a bomb that nearly obliterates the Kremlin, he is secretly tasked with exposing the real culprit, teaming with fellow agents Jane (Paula Patton) and Benji (Simon Pegg) and an intelligence analyst (Jeremy Renner) on a covert mission.—
Kevin Jacobsen,
Entertainment Weekly,
19 Jan. 2026
Adverb
-
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
-
In a way, I am being surreptitiously employed by the owner for two minutes.—
Francesco Pacifico,
The Dial,
9 Dec. 2025
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 31 Jan. 2026.
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