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
Joshua Siskin, Oc Register, 4 June 2026
Others have noted that police have nabbed underground treasure seekers from time to time.
—ABC News, 4 June 2026
Rachel Monroe, New Yorker, 14 May 2026
The Warsaw Rising Museum illustrates the plight of the Polish underground and the 63-day-long resistance against the German occupation.
—Kasia Dietz, Travel + Leisure, 13 May 2026
Literary Hub, 3 June 2026
The wells would extend roughly five miles underground, stretching beneath parts of Erie.
—Sarah Horbacewicz, CBS News, 3 June 2026
See All Example Sentences for underground
Adjective
One of these is the presence of an underground structure that stores starch and allows the plant to spread through the soil when growing conditions are good, and to rejuvenate from environmental stress should its above-ground growth die.
—Joshua Siskin, Oc Register, 4 June 2026
Others have noted that police have nabbed underground treasure seekers from time to time.
—ABC News, 4 June 2026
Noun
Though many people come to far West Texas for its isolation—the Unabomber’s slightly less reclusive brother did a stint here in the eighties, living at first in a crude underground shelter—Miller said that immigration-enforcement agents have been an intrusive presence for many years.
—Rachel Monroe, New Yorker, 14 May 2026
The Warsaw Rising Museum illustrates the plight of the Polish underground and the 63-day-long resistance against the German occupation.
—Kasia Dietz, Travel + Leisure, 13 May 2026
Adverb
Below them, clattering on a dozen parallel tracks, the trains were coming and going, arriving and departing, thundering underground.
—Literary Hub, 3 June 2026
The wells would extend roughly five miles underground, stretching beneath parts of Erie.
—Sarah Horbacewicz, CBS News, 3 June 2026
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
-
That similarly clandestine spot is tucked in the mail sorting room of Hotel Phillips downtown.—
Kansas City Star,
Kansas City Star,
29 May 2026
-
Nicknamed Zvezdny Gorodok, or Star City/Starry Town, this clandestine base of operations was built beside the Tsiolkovskaya railway station served by the Yaroslavl Railroad.—
Jeff Spry,
Space.com,
27 May 2026
Adjective
-
The house spans almost 5,400 square feet, plus an additional 2,200 square feet of finished subterranean space executed to the same standard as the rest of the house.—
Mark David,
Robb Report,
22 May 2026
-
These subterranean passageways are significant in Hawaiian culture, providing shelter for the ancient communities and and being places for ceremonies and burials.—
Kathleen Wong,
USA Today,
20 May 2026
Noun
-
The 50-bed facility to be built in one of Kenya’s largest air force bases was expected to be operational by Friday, but has faced massive resistance from opposition leaders, health workers, and civil society.—
Martin K.N Siele,
semafor.com,
29 May 2026
-
Today’s players are reminded of the labor battles their predecessors went through, and the resistance to any sort of salary limit is just as unyielding.—
Jim Alexander,
Oc Register,
29 May 2026
Adjective
-
Comeaux also said undercover officers would focus on drug enforcement.—
Matthew Ablon,
CBS News,
1 June 2026
-
The Washington Nationals are in full damage control after an undercover journalist with the O’Keefe Media Group caught now former Director of Community Relations Sean Hudson claiming to be religiously discriminating against Catholic starting pitcher Trevor Williams.—
Jon Root OutKick,
FOXNews.com,
30 May 2026
Adverb
-
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
-
The strategic insights that matter most—how to respond to a competitive threat, whether an acquisition makes sense, how to restructure around AI, and which leadership gaps are stealthily costing the company—are only partly products of rigorous thinking.—
Julian Hayes II,
Forbes.com,
27 May 2026
Adjective
-
In mid-January, as Iran crushed wide-scale protests with the mass killing of demonstrators, Israel prepared a covert mission along the Azerbaijan-Iran border, two of the sources familiar with the plans told CNN.—
Tal Shalev,
CNN Money,
5 June 2026
-
The facility's revelation came less than two years after North Korea unveiled another covert uranium-enrichment plant in September 2024, in its first public disclosure of such a facility since showing one at the country's main Yongbyon nuclear complex to visiting American scholars in 2010.—
CBS News,
CBS News,
4 June 2026
Adverb
-
Gray-hat hackers, unlike white-hats, surreptitiously sneak into corporate systems to find security vulnerabilities.—
Winston Cho,
HollywoodReporter,
4 June 2026
-
Scammers can create an AI replica of someone’s voice using a short recording of their speech — often pulled from social media or an earlier scam call that was surreptitiously recorded.—
CNN.com Wire Service,
Mercury News,
29 May 2026
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 9 Jun. 2026.
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