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
Elliott Wenzler, Denver Post, 14 Sep. 2025
There were quick glimpses of a Monty Mole burrowing underground, Cheep Cheeps swimming in a stream and Toads scurrying around the castle.
—Jordan Moreau, Variety, 12 Sep. 2025
Jessica Mathews, Fortune, 11 Sep. 2025
The garlic plants in the garden looked like mini underground palm trees with the top of the trees coming out of the ground.
—Manuel Muñoz, Literary Hub, 11 Sep. 2025
Jacob Orledge, ProPublica, 15 Aug. 2025
Boston’s Big Dig, which buried a central highway underground, was infamously plagued by cost overruns but eventually transformed the city’s urban landscape and boosted the economy.
—Tina Li, Sacbee.com, 14 Aug. 2025
See All Example Sentences for underground
Adjective
There could be unknowns underground because the site was used as a train yard, starting in 1871, when there were no environmental laws and no official records of what was being done on the property.
—Elliott Wenzler, Denver Post, 14 Sep. 2025
There were quick glimpses of a Monty Mole burrowing underground, Cheep Cheeps swimming in a stream and Toads scurrying around the castle.
—Jordan Moreau, Variety, 12 Sep. 2025
Noun
The Boring Company has received initial approvals to dig a 68-mile underground public transit system in the city.
—Jessica Mathews, Fortune, 11 Sep. 2025
The garlic plants in the garden looked like mini underground palm trees with the top of the trees coming out of the ground.
—Manuel Muñoz, Literary Hub, 11 Sep. 2025
Adverb
Millions of Americans own the rights to oil and gas underground.
—Jacob Orledge, ProPublica, 15 Aug. 2025
Boston’s Big Dig, which buried a central highway underground, was infamously plagued by cost overruns but eventually transformed the city’s urban landscape and boosted the economy.
—Tina Li, Sacbee.com, 14 Aug. 2025
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
-
Co-created by The New York Times bestselling author Carr and season 1 creator and showrunner David DiGilio, Dark Wolf follows Ben Edwards (Taylor Kitsch) on his journey from the SEALs to the clandestine side of CIA special operations.—
Susan Young,
PEOPLE,
11 Sep. 2025
-
The Bundy family’s statement noted this and said their destination was not clandestine, as the FBI document alleged.—
Nicole Blanchard,
Idaho Statesman,
7 Sep. 2025
Adjective
-
Just a few blocks from the festival is this subterranean boite, situated underneath Little Sister, an always-excellent Dutch-Indonesian restaurant.—
Kate Dingwall,
Forbes.com,
9 Sep. 2025
-
But while the area has been evacuated, a gang of robbers led by James is drilling into the subterranean vault of a nearby bank.—
Carole Horst,
Variety,
5 Sep. 2025
Noun
-
Both offenses are moving with little resistance thus far.—
Arkansas Online,
Arkansas Online,
14 Sep. 2025
-
This high-tech top is made from a fabric blend that combines the odor-resistance and quick-drying properties of merino wool with the wrinkle-resistant and thermoregulation properties of lyocell.—
Katie Jackson,
Travel + Leisure,
14 Sep. 2025
Adjective
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The two were to meet in the Salt Lake City area, where Nicholas Eller was to pay the undercover officer $130,000 for the marijuana.—
Judy L. Thomas,
Kansas City Star,
17 Sep. 2025
-
Eldin also sold drugs to an undercover DEA agent five times in 2023 and 2024, including one $1,200 deal for five ounces, authorities said in court filings.—
Nate Gartrell,
Mercury News,
16 Sep. 2025
Adverb
-
Karalis supplies his colleagues with fluorescent orange utility uniforms and stealthily leads them through the back door of the Bank Al Muraqabah, located just below Rahim’s building.—
Peter Debruge,
Variety,
6 Sep. 2025
-
Others are stealthily looking for deals, sales, using layaway options and trading brand preferences for affordability.—
Leah Olajide,
Freep.com,
26 Aug. 2025
Adjective
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Moreover, the lobster boat and the Mako were covert FBI assets carefully disguised as legitimate smuggling vessels.—
Martin Suarez,
Rolling Stone,
13 Sep. 2025
-
If compromised, malicious radios inside them could be used for simultaneous outages or covert data collection, the FHWA warned.—
Sujita Sinha,
Interesting Engineering,
11 Sep. 2025
Adverb
-
If some have surreptitiously slipped into the cart, throw them under the (school) bus.—
Catharine Kaufman,
San Diego Union-Tribune,
15 Sep. 2025
-
By the episode's end, however, he's set his sights on Morgan, having surreptitiously slipped a note into her grocery bag.—
Randall Colburn,
Entertainment Weekly,
6 Sep. 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 21 Sep. 2025.
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