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.
The couple certainly couldn’t admit who they really were: Yakob Rudnik and Tatyana Moiseenko, undercover Soviet agents for the Communist International, or Comintern.
From The Wall Street Journal ● Aug. 28, 2026
Their devotion to communism as unshakable as ever, both worked for the Soviet government—though in staid desk jobs rather than undercover operations—before dying within a month of each other in 1964.
From The Wall Street Journal ● Aug. 28, 2026
I slipped out of bed to peer into the brown bag holding my new undercover possession when I suddenly realized I didn’t remember bringing the bag home.
From Los Angeles Times ● Aug. 14, 2026
A BBC undercover investigation in 2025 found nurses and pharmacists supplying Botox without carrying out the face-to-face consultations required under professional guidance.
From BBC ● Jul. 5, 2026
White took over as the warden of the federal penitentiary in Atlanta, where he led an undercover operation to catch officials who, in exchange for bribes, were granting prisoners nicer living conditions and early releases.
From "Killers of the Flower Moon" by David Grann
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.
