under cover

1 of 3

phrase

1

: in an envelope or wrapper

2

: under concealment : in secret

undercover

2 of 3

adjective

un·​der·​cov·​er ˌən-dər-ˈkə-vər 

: acting or executed in secret

specifically : employed or engaged in spying or secret investigation

an undercover agent

undercover adverb

undercover

3 of 3

noun

: a person engaged in undercover activity : spy

Synonyms of under cover

Adjective

• clandestine
• underground
• covert
• sneak
• private

Noun

• spy
• operative
• agent

Examples of under cover in a Sentence

Adjective

an undercover operation to infiltrate the terrorist organization

for months she's been an undercover agent pretending to be a drug dealer

Noun

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

Recent Examples on the Web

Phrase

That same teen sensation left West Africa due to troubles from its dictatorship, and moved to Paris under cover of night and a clandestine air flight. — A.d. Amorosi, Variety, 18 Aug. 2026

Nolan divides the sacking of Troy into two lengthy sequences, both shot under cover of darkness but edited (by Jennifer Lame) with a magisterial clarity. — Justin Chang, New Yorker, 17 July 2026

Adjective

By mid-July, an undercover FBI informant posing as an ISIS facilitator was messaging with her. — Lila Dominus, CNN Money, 20 Aug. 2026

An undercover officer posing as a UPS driver saw Vargas, 35, outside the building where the packages were being shipped, prosecutors said. — Alexa Herrera, CBS News, 19 Aug. 2026

Noun

Federal prosecutors accused Heidi Beirich, an expert on political extremism and a former director of the nonprofit’s intelligence project, of overseeing payments to informants working undercover in a variety of hate groups. — Jeremy Roebuck, Washington Post, 12 Aug. 2026

Goode and the Safdies began filming interviews with Tabraue and Crutchfield in 2014, with Josh sporting spy-camera glasses to try to capture Tabraue undercover, but the footage looked like crap. — Marlow Stern, Variety, 6 Aug. 2026

Word History

First Known Use

Adjective

1920, in the meaning defined above

Noun

1962, in the meaning defined above

Rhymes for under cover

• rediscover
• undercover
• discover
• hardcover
• recover
• thereover
• uncover
• hover
• plover

Kids Definition

undercover

adjective

un·​der·​cov·​er

-ˌkəv-ər

: acting or performed in secret

an undercover scheme

especially : employed or engaged in spying or secret investigation

an undercover agent

undercover adverb