undercover

1 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

2 of 3

noun

: a person engaged in undercover activity : spy

under cover

3 of 3

phrase

1

: in an envelope or wrapper

2

: under concealment : in secret

Synonyms of undercover

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

The drama mixes battlefield action with a tale of conflicted allegiances and the dangers of undercover work in hostile territory. — Naman Ramachandran, Variety, 10 Oct. 2026

After the police were tipped off to Noye, undercover detectives were sent to surveil him. — Frannie Comstock, Encyclopedia Britannica, 9 Oct. 2026

Noun

Some retired employees who worked undercover might need protection services like relocation assistance or even name changes if their data is exposed publicly. — Jenna McLaughlin, NPR, 30 Sep. 2026

Unlike its restaurant reviewers, who are anonymous and work undercover, Michelin’s winery experts had to make appointments at each winery to evaluate several vintages of the wine as well as the vineyards and winemaking facilities. — Mike Desimone, Robb Report, 20 Sep. 2026

Phrase

In the back rooms, Rana teaches mathematics for free, alongside women running secret lessons in English and computer skills under cover of sewing and beadwork. — Mark Sappenfield, Christian Science Monitor, 9 Oct. 2026

The titular bed trick refers to the literary device, beloved by Shakespeare and by opera buffa, in which a lover sneaks into a bed and, under cover of darkness, is taken for someone else. — S. C. Cornell, New Yorker, 29 Sep. 2026

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