1
as in clandestine
undertaken or done so as to escape being observed or known by others
an undercover operation to infiltrate the terrorist organization
Synonyms & Similar Words
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Antonyms & Near Antonyms
as in spy
a person who tries secretly to obtain information for one country in the territory of another usually unfriendly country
within the city was a well-organized fifth column, and these undercovers would make themselves known as soon as the invading forces breached the city limits
Synonyms & Similar Words
as in underground
Related Words
Dissimilar Words
Example Sentences
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Recent Examples of undercover
Eduardo Cuevas, USA Today, 7 Feb. 2026
The business, Caskets of Honor, was fined after an undercover investigation by the Oklahoma Funeral Board.
—Dale Denwalt, Oklahoman, 6 Feb. 2026
Dana Taylor, USA Today, 22 Aug. 2025
He is aided by Yasir Abbas, a weapons specialist; Raghuveer Singh, a sniper who served in Kashmir and Tawang; Uday Bhan, an explosives expert; and Sukhbir Singh, an Indian agent undercover in Pakistan posing as a Karachi stockbroker.
—Time, 13 Aug. 2025
See All Example Sentences for undercover
Adjective
Police said Duprey was trying to evade police on a friend’s scooter after he was allegedly caught selling drugs in an undercover sting.
—Eduardo Cuevas, USA Today, 7 Feb. 2026
The business, Caskets of Honor, was fined after an undercover investigation by the Oklahoma Funeral Board.
—Dale Denwalt, Oklahoman, 6 Feb. 2026
Noun
Law enforcement officers working in plain clothes or undercover is nothing new.
—Dana Taylor, USA Today, 22 Aug. 2025
He is aided by Yasir Abbas, a weapons specialist; Raghuveer Singh, a sniper who served in Kashmir and Tawang; Uday Bhan, an explosives expert; and Sukhbir Singh, an Indian agent undercover in Pakistan posing as a Karachi stockbroker.
—Time, 13 Aug. 2025
See All Example Sentences for undercover
Recent Examples of Synonyms for undercover
Adjective
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Ortiz said Rodríguez Torres went further by overseeing the creation of clandestine detention facilities.—
Antonio María Delgado,
Miami Herald,
10 Feb. 2026
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Yes, its signage and entryway are on the clandestine side.—
Josh Miller,
Southern Living,
10 Feb. 2026
Adjective
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The historic Vietnamese revolutionary Ho Chi Minh is said to have used the hotel as a covert meeting spot during the First Indochina War.—
Sofia Celeste,
Footwear News,
14 Feb. 2026
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What else is going on A Southern California man was sentenced to four years in prison for acting as a covert Chinese agent while helping elect an Arcadia City Council member.—
James Rainey,
Los Angeles Times,
11 Feb. 2026
Noun
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He was also sanctioned by the European Union in January 2019 following a nerve agent attack in Salisbury, England, which the British government said was carried out by GRU agents to poison a former Russian spy.—
Anna Chernova,
CNN Money,
6 Feb. 2026
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That unusual role for a spy chief raised additional questions from Democrats on the House and Senate intelligence committees.—
DAVID KLEPPER THE ASSOCIATED PRESS,
Arkansas Online,
5 Feb. 2026
Adverb
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In Silo, references to a toxic world imply that half a million people were sent underground to protect them from the horrors of a nuclear holocaust.—
Richard Edwards,
Space.com,
7 Feb. 2026
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Arranged in grids that connect to low-Earth-orbit satellites, the nodes are capable of collecting and sharing data used to create high-resolution maps of anomalies, miles underground, that might be gold, copper, nickel, lithium, or other minerals.—
Lauren Steele,
The Atlantic,
7 Feb. 2026
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
Adjective
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Sharon used to be the company’s secret weapon, a beautiful, smart and immaculately presented businesswoman who flattered hard cash out of horny old billionaires.—
Damon Wise,
Deadline,
11 Feb. 2026
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Typical zero-knowledge proofs require a demonstration of how to build what’s called a simulator, which can re-create the steps of the proof without actually knowing the secret solution.—
Peter Hall,
Scientific American,
11 Feb. 2026
Noun
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This strategy of sending the notes to the media could be designed to ratchet up pressure, said Eric O’Neill, a former FBI counterintelligence operative and cybersecurity expert.—
Chris Kenning,
USA Today,
8 Feb. 2026
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That unnamed co-conspirator is widely believed to be longtime Oakland political operative Mario Juarez, who twice ran for City Council himself but was never elected.—
Jakob Rodgers,
Mercury News,
6 Feb. 2026
Adverb
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Callella, 42, is accused of using a voice over internet protocol text and call application to surreptitiously reach out to the family, but authorities were able to link the phone number to his email address and, later, his residence, according to the complaint.—
Richard Winton,
Los Angeles Times,
6 Feb. 2026
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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
Cite this Entry
“Undercover.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/undercover. Accessed 15 Feb. 2026.
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