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.
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
To confirm it was Jamal, we made an undercover visit to one of the shops where he was staffing the till, and started a conversation.
From BBC ● Jul. 2, 2026
In 2005, an undercover investigator from the FDA called the farm and was told the milk was safe for human consumption.
From Salon ● Jun. 22, 2026
He plays Martian, a veteran CIA operative whose years undercover have left their mark.
From BBC ● Jun. 20, 2026
Plutarch Heavensbee has been, for several years, part of an undercover group aiming to overthrow the Capitol.
From "Catching Fire" by Suzanne Collins
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.
