adj.秘密的，隐蔽的,
Merriam-Webster Online Dictionary
clandestine (adjective)marked by, held in, or conducted with - secrecy surreptitious a clandestine love affair secret
Merriam-Webster Online Thesaurus
clandestine (adjective)undertaken or done so as to escape being observed or known by others
SYNONYMS:
backstairs, behind-the-scenes, clandestine, covert, furtive, hole-and-corner, hugger-mugger, hush-hush, private, privy, sneak, sneaking, sneaky, stealth, stealthy, surreptitious, undercover, underground, underhand, underhandedRELATED WORDS:
back-channel, closed-door, off-the-books, off-the-record; classified, confidential, restricted, top secret, undisclosed; concealed, hidden, secreted, subterranean, unadvertised, unexposedNEAR ANTONYMS:
acknowledged, avowed; aboveboard, straightforward, unconcealed, undisguised; unclassified, unrestricted; clear, evident, manifest, obvious, patent, plain