undercover

1 of 2

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

2 of 2

noun

: a person engaged in undercover activity : spy

Synonyms

Adjective

• clandestine
• underground
• covert
• sneak
• private

Noun

• spy
• operative
• agent

Examples of undercover 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

Adjective

Eldin also sold drugs to an undercover DEA agent five times in 2023 and 2024, including one $1,200 deal for five ounces, authorities said in court filings. —Nate Gartrell, Mercury News, 16 Sep. 2025

Middleboro detectives launched an undercover operation and took control of the child’s phone, as police texted with the suspect. —Rick Sobey, Boston Herald, 15 Sep. 2025

Noun

Four other agents accompanied me, all also operating undercover. —Martin Suarez, Rolling Stone, 13 Sep. 2025

Season 2 of the hit Paramount+ series will continue following Martian (Michael Fassbender), a CIA agent living undercover in his own life. —Max Goldbart, Deadline, 4 Sep. 2025

Word History

First Known Use

Adjective

1920, in the meaning defined above

Noun

1962, in the meaning defined above

Rhymes for undercover

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

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