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

The ships would travel under cover of darkness, often in convoys that sailed close together and hugged the Omani coast, according to two people familiar with the matter. — Weilun Soon, Fortune, 5 July 2026

Dowding sows both leeks and celeriac under cover in module trays at the same time, around mid-March. — Sj McShane, Martha Stewart, 30 June 2026

Adjective

Duties include developing operation plans and going undercover. — Sacbee.com, 7 July 2026

In exchange, one of the agents asked Lumumba to move the city’s deadline for the hotel project from April 30 to April 10 or 15, giving the undercover FBI agents an advantage over other developers. — Natalie Neysa Alund, USA Today, 6 July 2026

Noun

The result is that the majority — roughly 70% of public firms — of Self-Dealers and Value-Extractors still practicing MSV undercover are enjoying below-average as shown by the data in Figure 2 from Professor Felix Oberholzer’s book Better Simpler Strategy. — Steve Denning, Forbes.com, 21 June 2026

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

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