clandestine

adjective

clan·​des·​tine klan-ˈde-stən 

also -ˌstīn

or -ˌstēn

or ˈklan-də-

: marked by, held in, or conducted with secrecy : surreptitious

a clandestine love affair

clandestinely adverb

clandestineness noun

clandestinity

ˌklan-də-ˈsti-nə-tē 

-de-ˈsti-

noun

Did you know?

Psst!—if your first instinct, upon being asked what you’ve been up to, is to clam up, your querier may suspect you’ve been involved in some clandestine activities. Clandestine often substitutes for secret and covert, and it is commonly applied to actions that involve secrecy maintained for an evil, illicit, or unauthorized purpose, as in "clandestine activities pursued under cover of night." It comes to English by way of Middle French, from the Latin word clandestinus, which is itself from the Latin adverb clam, meaning "secretly." Note that this clam is not the ancestor of the English word clam, despite how tightly sealed and thus secretive the bivalves may seem.

Synonyms of clandestine

• undercover
• covert
• underground
• sneak
• private
• surreptitious

Choose the Right Synonym for clandestine

secret, covert, stealthy, furtive, clandestine, surreptitious, underhanded mean done without attracting observation.

secret implies concealment on any grounds for any motive.

met at a secret location

covert stresses the fact of not being open or declared.

covert intelligence operations

stealthy suggests taking pains to avoid being seen or heard especially in some misdoing.

the stealthy step of a burglar

furtive implies a sly or cautious stealthiness.

lovers exchanging furtive glances

clandestine implies secrecy usually for an evil, illicit, or unauthorized purpose and often emphasizes the fear of being discovered.

a clandestine meeting of conspirators

surreptitious applies to action or behavior done secretly often with skillful avoidance of detection and in violation of custom, law, or authority.

the surreptitious stockpiling of weapons

underhanded stresses fraud or deception.

an underhanded trick

Examples of clandestine in a Sentence

The clandestine meetings, the passing back and forth of messages between Lodge and the plotters, the coaxing along of the generals, all had the emotional lift of a strong amphetamine. —Neil Sheehan, A Bright Shining Lie, 1988

The CIA's great innovation has been to concentrate in peacetime on 'covert action'—that is, the use of clandestine means to challenge policies and regimes in other countries. —Arthur M. Schlesinger, Jr., The Cycles of American History, 1986

And Pym was in London for a conference—no, he wasn't, he was attending a three-day course on the latest methods of clandestine communication in a beastly little training house off Smith Square. —John le Carré, A Perfect Spy, 1986

I took a clandestine peek at the price tag on the diamond necklace.

Recent Examples on the Web

Earlier this month, state officials reported dismantling a clandestine drug laboratory located south of Ensenada, marking the ninth such laboratory shut down by authorities in the span of a year. —Alexandra Mendoza, San Diego Union-Tribune, 15 Feb. 2026

Ortiz said Rodríguez Torres went further by overseeing the creation of clandestine detention facilities. —Antonio María Delgado, Miami Herald, 10 Feb. 2026

Yes, its signage and entryway are on the clandestine side. —Josh Miller, Southern Living, 10 Feb. 2026

Nearly a quarter of the trips documented in the inspector general’s report were to Canada, where LAPD personnel traveled to learn about best practices in investigating human trafficking and clandestine drug labs. —Los Angeles Times, 7 Feb. 2026

Word History

Etymology

Middle French or Latin; Middle French clandestin, from Latin clandestinus, from clam secretly; akin to Latin celare to hide — more at hell

First Known Use

circa 1528, in the meaning defined above

Rhymes for clandestine

• intestine
• progestin

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Kids Definition

clandestine

adjective

clan·​des·​tine klan-ˈdes-tən 

: done in secret

a clandestine meeting

clandestinely adverb