From WordNet (r) 2.0 (August 2003) [wn]:
furtive
adj 1: marked by quiet and caution and secrecy; taking pains to
avoid being observed; "a furtive manner"; "a lurking
prowler"; "a sneak attack"; "stealthy footsteps"; "a
surreptitious glance at his watch"; "someone skulking
in the shadows" [syn: lurking, skulking,
{sneak(a)}, sneaky, stealthy, surreptitious]
2: secret and sly or sordid; "backstairs gossip"; "his low
backstairs cunning"- A.L.Guerard; "backstairs intimacies";
"furtive behavior" [syn: backstair, backstairs]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Furtive \Fur"tive\, a. [L. furtivus, fr. furtum theft, fr. fur
thief, akin to ferre to bear: cf. F. furtif. See Fertile.]
Stolen; obtained or characterized by stealth; sly; secret;
stealthy; as, a furtive look. --Prior.
[1913 Webster]
A hasty and furtive ceremony. --Hallam.
[1913 Webster]