The Collaborative International Dictionary of English v.0.48:
Clandestine \Clan*des"tine\, a. [L. clandestinus, fr. clam
secretly; akin to celare, E. conceal: cf. F. clandestin.]
Conducted with secrecy; withdrawn from public notice, usually
for an evil purpose; kept secret; hidden; private; underhand;
as, a clandestine marriage. --Locke.
Syn: Hidden; secret; private; concealed; underhand; sly;
stealthy; surreptitious; furtive; fraudulent. --
Clan*des"tine*ly, adv. -- Clan*des"tine*ness, n.
[1913 Webster]