1. Furtif.
2. Illicite.
ETYM Latin furtivus, from furtum theft, from fur thief, akin to ferre to bear: cf. French furtif. Related to Fertile.
Marked by quiet and caution and secrecy; taking pains to avoid being observed; SYN. lurking, skulking, sneak, sneaky, stealthy, surreptitious.
ETYM Latin surreptitius, or subreptitius, from surripere, subripere, to snatch away, to withdraw privily; sub- under + rapere to snatch. Related to Sub-, and Ravish.
Done or made by stealth, or without proper authority; made or introduced fraudulently; clandestine.