Clandestine

Part of speech: adjective (a.)

Conducted with secrecy; withdrawn from public notice, usually for an evil purpose; kept secret; hidden; private; underhand; as, a clandestine marriage. Locke.

Synonyms: Hidden; secret; private; concealed; underhand; sly; stealthy; surreptitious; furtive; fraudulent. Clan*des"tine*ly, adv. Clan*des"tine*ness, n.