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 investigation by the organisation looked into a separate firm in the city which had served an undercover officer gluten-free food that was later found to contain high levels of gluten.

From BBC

A British diplomat has been ordered to leave Russia, with officials accusing the man of being an intelligence agent working undercover at the embassy in Moscow.

From BBC

There were only a few other riders in our railcar, but I knew how important it was to remain undercover.

From Literature

Realising undercover police officers were waiting off court was the moment Oliver Anderson knew he had been rumbled.

From BBC

A week earlier Sturdivant had also begun communicating on a social-media platform with someone who, unbeknown to him, was an undercover officer.

From The Wall Street Journal

Related Words

• covert