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
Examples are automatically compiled from online sources to
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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
Sharon Wu,
USA Today,
16 June 2026
The Kyiv-Pechersk Lavra, also known as the Monastery of the Caves, is a sprawling complex of monasteries and churches, including some underground, built from the 11th to the 19th century.
—
ABC News,
14 June 2026
Mrigakshi Dixit,
Interesting Engineering,
17 June 2026
With reddish-brown bodies, fire ants travel in swarms and build large colonies deep underground.
—
Olivia McIntosh,
Martha Stewart,
17 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.
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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
Stinging insects have nested in a wall or underground.
—
Sharon Wu,
USA Today,
16 June 2026
The Kyiv-Pechersk Lavra, also known as the Monastery of the Caves, is a sprawling complex of monasteries and churches, including some underground, built from the 11th to the 19th century.
—
ABC News,
14 June 2026
Adverb
The plan is to compress the green hydrogen gas and pump it deep underground for storage within custom-engineered, lined rock caverns.
—
Mrigakshi Dixit,
Interesting Engineering,
17 June 2026
With reddish-brown bodies, fire ants travel in swarms and build large colonies deep underground.
—
Olivia McIntosh,
Martha Stewart,
17 June 2026
See All Example Sentences for underground
Recent Examples of Synonyms for underground
Adjective
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Some may be announced publicly; others may happen in more clandestine ways.
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But clandestine flows aren’t the biggest factor behind the market calm.
Adjective
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Nearby, the subterranean Cisternerne gallery offers an eerie, atmospheric art experience in former water reservoirs.
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One type of subterranean termite worth noting is the Formosan termite (Coptotermes formosanus).
Noun
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Meanwhile, existing antibiotics have been overused, and resistance has mounted to critical levels.
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Hussein’s killing cemented the schism between Sunni and Shiite Islam and remains a powerful symbol of resistance against oppression and injustice.
Adverb
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The six-suite Baines’ Lodge, though, has stealthily sneaked past them all as an existing camp that has received a thoughtful, artful makeover from operator Abercrombie & Kent.
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Ernest has been stealthily making deals, investing nearly $500 million into some of the world’s hottest technology companies, including SpaceX, Anthropic and Jeff Bezos’ new artificial intelligence startup, Prometheus, which is the firm’s largest investment to date.
Adjective
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According to his plea agreement with prosecutors, Doyle sold a Glock pistol to an undercover informant on May 20, 2025 — part of a series of transactions on Chicago’s South Side that led to his arrest on July 7, 2025, a few days after the shooting at his daughter’s party.
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Whether openly or undercover, MSV doesn’t just fail shareholders.
Adverb
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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.
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Gray-hat hackers, unlike white-hats, surreptitiously sneak into corporate systems to find security vulnerabilities.
Adjective
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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.
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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.
Adverb
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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.
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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.
Cite this Entry
“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 27 Jun. 2026.
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