undercover
adjective
[ ʌndəˈkʌvə ]
• involving secret work within a community or organization, especially for the purposes of police investigation or espionage.
• "an undercover police operation"
Similar:
covert,
secret,
clandestine,
private,
confidential,
conspiratorial,
underground,
surreptitious,
furtive,
cloak-and-dagger,
hole-and-corner,
hugger-mugger,
back-alley,
backstair,
stealthy,
closet,
intelligence,
hidden,
concealed,
masked,
veiled,
shrouded,
black,
hush-hush,
sneaky,
