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.
“Gordon Ramsay’s Secret Service,” a follow-up series that debuted in 2025, pushed the premise further still: undercover helpers, surveillance, insiders and Ramsay comparing the operation to going “full on MI6” with restaurants.
From Salon ● Jul. 5, 2026
Its officers, who wear civilian clothes, have a network of undercover agents and informants dedicated to monitoring and infiltrating dissident movements and independent groups such as art collectives.
From The Wall Street Journal ● Jul. 5, 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
Investigators later found that "no authorised undercover operation involving precious metals existed at the time" but instead Khan, and another officer "instructed officers" to release the businessman, prosecutors said in May.
From BBC ● Jun. 29, 2026
She added that she wasn’t “concerned with burying things,” but with “digging up” undercover messages.
From "The Woman All Spies Fear" by Amy Butler Greenfield
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.
