undercover

American  

[uhn-der-kuhv-er, uhn-der-kuhv-] / ˌʌn dərˈkʌv ər, ˈʌn dərˌkʌv- /

adjective

1. working or done out of public sight; secret.

   an undercover investigation.

   Synonyms:

   hidden, clandestine, covert

2. engaged in spying or securing confidential information.

   an undercover agent.

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undercover British  

/ ˌʌndəˈkʌvə /

adjective

1. done or acting in secret

   undercover operations

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Etymology

Origin of undercover

First recorded in 1850–55; under- + cover

Example Sentences

Another appears to instruct Claude Code in some cases to go “undercover” and not reveal that it is an AI when publishing code to platforms like GitHub.

From The Wall Street Journal

But an undercover DEA investigation targeting Honduras’s government, led by the agency’s elite Special Operations Division, unexpectedly ensnared the nephews.

From The Wall Street Journal

The alleged plot began early last month, when authorities say Heifler took part in a 10 February video call with a "self-defence" group that included an undercover law enforcement officer.

From BBC

The lawsuit was the result of an undercover investigation into Meta’s platforms that created decoy profiles posing as children aged 14 years and younger.

From The Wall Street Journal

The stranger, however, arrived at the rendezvous accompanied by undercover police officers, who arrested the man.

From The Wall Street Journal

Related Words

• covert