形容詞 furtive:

1. marked by quiet and caution and secrecy; taking pains to avoid being observed
   同義詞：sneak, sneaky, stealthy, surreptitious
2. secret and sly or sordid
   同義詞：backstair, backstairs

1. In a furtive or circumspect manner; indirectly.
   行為鬼祟的或謹慎的; 謹慎的
2. He cast a furtive glance at her.
   他偷偷瞥了她一眼。
3. That person was furtive and did not want to be noticed.
   那人鬼鬼祟祟的并不想讓人注意。
4. They are making a furtive movement.
   他們正做一項詭秘的行動。

fur.tive

adj.（形容詞）
Characterized by stealth; surreptitious.
秘密的：偷偷摸摸的；鬼鬼祟祟的
Expressive of hidden motives or purposes; shifty.See Synonyms at secret
詭詐的：有不可告人的動機或目的的；?；ㄕ械膮⒁?secret

來源：
French furtif
法語 furtif
from Old French
源自 古法語
from Latin furtovus
源自 拉丁語 furtovus
from furtum [theft]
源自 furtum [偷竊行為]
from fôr [thief] * see bher-
源自 fôr [小偷] *參見 bher-

【引伸】
fur.tively
adv.（副詞）
fur.tiveness
n.（名詞）