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
Tom Tapp, Deadline, 15 Oct. 2025
Many parallels exist between being high above the Earth and deep underground.
—Kenna Hughes-Castleberry, Space.com, 14 Oct. 2025
Joshua Siskin, Oc Register, 25 Oct. 2025
In 1944, Republicans called the construction of an underground bunker and offices within the East Wing wasteful and accused FDR of using the White House makeover to improve his image, the WHHA said on its website.
—Ryan Mancini, The Hill, 24 Oct. 2025
Joseph Hernandez
august 20, Kansas City Star, 20 Aug. 2025
Millions of Americans own the rights to oil and gas underground.
—Jacob Orledge, ProPublica, 15 Aug. 2025
See All Example Sentences for underground
Adjective
A week later the same fire, which had likely smoldered underground, reemerged and became known as the Palisades Fire.
—Tom Tapp, Deadline, 15 Oct. 2025
Many parallels exist between being high above the Earth and deep underground.
—Kenna Hughes-Castleberry, Space.com, 14 Oct. 2025
Noun
Along with bulbs, tubers, and rhizomes, corms constitute the quartet of underground storage structures that send up their silky blooms once a year — or more, in the case of remontant (repeat-blooming) irises and daylilies.
—Joshua Siskin, Oc Register, 25 Oct. 2025
In 1944, Republicans called the construction of an underground bunker and offices within the East Wing wasteful and accused FDR of using the White House makeover to improve his image, the WHHA said on its website.
—Ryan Mancini, The Hill, 24 Oct. 2025
Adverb
Alternative rock band Goo Goo Dolls have been active in the music scene for nearly 40 years, getting their start in Buffalo, New York’s underground.
—Joseph Hernandez
august 20, Kansas City Star, 20 Aug. 2025
Millions of Americans own the rights to oil and gas underground.
—Jacob Orledge, ProPublica, 15 Aug. 2025
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
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Duplicity, directed by Tony Gilroy, follows two corporate spies, Claire (Roberts) and Ray (Owen), who become embroiled in a clandestine love affair.—
Carly Thomas,
HollywoodReporter,
14 Oct. 2025
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There’s a clandestine quality to it all.—
Roxana Hadadi,
Vulture,
14 Oct. 2025
Adjective
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The subterranean passageway shown to her by a residence staffer provided some relief.—
Darlene Superville,
Denver Post,
26 Oct. 2025
-
The hotel's new subterranean spa will debut in spring 2026 with a full slate of wellness offerings.—
Sarah Bruning,
Travel + Leisure,
24 Oct. 2025
Noun
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Reagan empowered Afghanistan’s resistance to the Soviet invasion – escalating Soviet losses and fueling discontent.—
Kathleen Collins,
Twin Cities,
26 Oct. 2025
-
The shelter had initially been targeted for a July 2025 opening, and has encountered fierce resistance from parts of the West Roxbury community since the state first began sharing its intention to house homeless families there last spring.—
Gayla Cawley,
Boston Herald,
26 Oct. 2025
Adjective
-
Billitier did have a hell of a story to tell about his decades of undercover work for the FBI, including several years infiltrating a Colombian drug ring in Texas.—
Steve Belanger,
HollywoodReporter,
23 Oct. 2025
-
The movie is based on the 1980s TV series, starring Don Johnson and Philip Michael Thomas, as undercover detectives in South Florida.—
Angelique Jackson,
Variety,
23 Oct. 2025
Adverb
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The song – and the band – stealthily established a place in culture by assisting people through big personal moments, both in solitude and with company.—
Tom Roland,
Billboard,
16 Oct. 2025
-
Yet, the number of in-person days coming down the pipeline has been stealthily increasing.—
Nick Lichtenberg,
Fortune,
9 Oct. 2025
Adjective
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The Institute for the Study of War (ISW) said on Friday the incident and the recent air incursion linked to Moscow show Kremlin plans for covert and overt attacks against Europe to prepare for a possible NATO-Russia war.—
Brendan Cole,
MSNBC Newsweek,
25 Oct. 2025
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The device is intended for intelligent underwater detection, real-time environmental monitoring, and potentially covert reconnaissance missions worldwide.—
Bojan Stojkovski,
Interesting Engineering,
25 Oct. 2025
Adverb
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Pavlick allegedly placed the camera under the toilet seat and surreptitiously videotaped dozens of adults and children, police said, KCRG reports.—
KC Baker,
PEOPLE,
21 Oct. 2025
-
Robert surreptitiously attains Alfred’s workbook/diary, where many secrets may exist.—
Kirk Honeycutt,
HollywoodReporter,
20 Oct. 2025
Adjective
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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 28 Oct. 2025.
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