conducted with or marked by hidden aims or methods; "clandestine intelligence operations"; "cloak-and-dagger activities behind enemy lines"; "hole-and-corner intrigue"; "secret missions"; "a secret agent"; "secret sales of arms"; "surreptitious mobilization of troops"; "an undercover investigation"; "underground resistance"
Undercover work involves secretly obtaining information for the government or the police. an undercover operation designed to catch drug smugglers. undercover reporters. Undercover is also an adverb. Swanson persuaded Hubley to work undercover to capture the killer. undercover work is done secretly by the police in order to catch criminals or find out information