clandestine; cloak-and-dagger; hole-and-corner; hugger-mugger; hush-hush; secret; surreptitious; undercover; undergroundconducted 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" |