undercover
Americanadjective
-
working or done out of public sight; secret.
an undercover investigation.
- Synonyms:
- hidden, clandestine, covert
-
engaged in spying or securing confidential information.
an undercover agent.
adjective
Etymology
Origin of undercover
Explanation
Undercover means secret or disguised. A police department might send undercover officers dressed as clowns to investigate a corrupt circus. When this adjective was originally used in the mid-19th century, it meant "sheltered beneath something," but after a century or so, it was routinely used to mean "covert or clandestine." If you go undercover, you're doing some kind of secret work, usually inside an organization or group. If the other chess club members want you to be an undercover spy inside the French club, you'll have to brush up on your verb tenses.
Vocabulary lists containing undercover
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Steve Coogan is terrific in a rare dramatic role, as is Tom Burke as cop teetering on the edge as he falls dangerously deep into his undercover persona.
From MarketWatch • May 31, 2026
On the other hand, these aggregators are bringing news stories to audiences who might not be getting them elsewhere – some of the undercover voters wouldn't otherwise be seeing much about politics.
From BBC • May 16, 2026
The caller even provided a “code phrase” that the victim was supposed to say to the alleged undercover officer at their meeting.
From Los Angeles Times • May 13, 2026
Last week, an undercover BBC report revealed how some self-described sleep experts have been giving new parents advice that goes against long-established safer sleep NHS guidelines.
From BBC • May 12, 2026
Later, the Agency sent an inexperienced undercover agent, codenamed COMPASS, to pose as a janitor at a residence hall for American embassy staff in Moscow.
From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
