1. (adj)furtive, sneak(a), sneaky, stealthy, surreptitious marked by quiet and caution and secrecy; taking pains to avoid being observed Antonyms: overt, unconcealed, open
2. (adj)clandestine, cloak-and-dagger, hole-and-corner(a), hugger-mugger, hush-hush, secret, surreptitious, undercover, underground conducted with or marked by hidden aims or methods Antonyms: unconcealed, overt, open