UNDER COVER Synonyms: 96 Similar and Opposite Words

undercover 1 of 3

adjective

ˌən-dər-ˈkə-vər

Definition of undercover

as in clandestine

undertaken or done so as to escape being observed or known by others an undercover operation to infiltrate the terrorist organization

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Antonyms & Near Antonyms

as in covert

working on missions in which one's objectives, activities, or true identity are not publicly revealed for months she's been an undercover agent pretending to be a drug dealer

Synonyms & Similar Words

Antonyms & Near Antonyms

overt

undercover

2 of 3

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

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undercover

3 of 3

adverb

as in underground

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Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of undercover

Adjective

The action film follows cop Brian O'Conner (Walker) going undercover to join the street racing crew led by Dominic Toretto (Diesel). — Caroline Blair, PEOPLE, 23 June 2026 In 1979 two undercover police officers ticketed 125 guests and criminally charged nine others. — Aki Nace, CBS News, 25 June 2026

Noun

Le, who was working undercover, was shot while inside his vehicle after responding to one of multiple burglaries at a cannabis business on Embarcadero near Fifth Ave. — Carlos E. Castañeda, CBS News, 11 Dec. 2025 First, in February 2008, a Dutch TV station aired a confession allegedly made by van der Sloot and captured on a hidden camera by Patrick van der Eem, a businessman working undercover for a Dutch journalist. — Lynsey Eidell, PEOPLE, 30 May 2026 See All Example Sentences for undercover

Recent Examples of Synonyms for undercover

Adjective

That was a concern because other research has indicated the Chinese government has, at times, delayed public disclosure of vulnerabilities submitted to the program so they could later be used in clandestine cyberattacks.

— Thomas Brewster, Forbes.com, 30 June 2026
The screening usually focusses on clandestine hanky-panky, but this season the girls’ irreverence was so abundant that the producers treated them to an unprecedented second viewing night.

— Lillian Fishman, New Yorker, 27 June 2026

Definition of clandestine

Adjective

To achieve this, Israel employed airstrikes, cyberattacks, interdictions of weapons and covert action to impede Iran’s ability to resupply Hezbollah’s existing arsenal and supply it with more advanced weapons.

— Amy McAuliffe, The Conversation, 26 June 2026
After 1996, when the protease inhibitors were developed, the duty to warn continued to be an important standard when HIV status became more clinically covert.

— M. Sara Rosenthal, STAT, 25 June 2026

Definition of covert

Noun

As expected, Carly didn’t take the bait, reproaching Z for referring to her daughter by her last name, spy style.

— Ryan Coleman, Entertainment Weekly, 6 July 2026
Outside of spy movies, documents rarely self-destruct after they’re read — and fortunately for mathematicians, proofs are no exception.

— Ben Brubaker, Quanta Magazine, 6 July 2026

Definition of spy

Adverb

Teams from the United States, France, and Venezuela together freed a father and his son after four days underground.

— Luis E. Romero, Forbes.com, 1 July 2026
Fleming staked much of his campaign on opposition to carbon capture and sequestration, the process for injecting carbon dioxide waste underground to reduce industrial pollution.

— ABC News, ABC News, 27 June 2026

Definition of underground

Adjective

Adding this recipe's not-so-secret ingredient, Bisquick, is a game changer for classic sausage balls.

— Hallie Milstein, Southern Living, 1 July 2026
Martin Sheen is the Army captain tasked with going on a secret mission to Cambodia to assassinate a special forces officer (Marlon Brando) who's gone rogue and might actually be nuts.

— Brian Truitt, USA Today, 1 July 2026

Definition of secret

Adverb

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.

— Chris Willman, Variety, 7 June 2026
Gray-hat hackers, unlike white-hats, surreptitiously sneak into corporate systems to find security vulnerabilities.

— Winston Cho, HollywoodReporter, 4 June 2026

Definition of surreptitiously

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“Undercover.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/undercover. Accessed 8 Jul. 2026.

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Synonyms of undercover

adjective

noun

adverb

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