furtive
adjective uk/ˈfɜː.tɪv/ us/ˈfɝː.t̬ɪv/
（人）偷偷摸摸的；鬼鬼祟祟的；（行动）秘密的
(of people) behaving secretly and often dishonestly, or (of actions) done secretly and often dishonestly
I saw him cast a furtive glance at the woman at the table to his right. 我看到他偷偷地扫了一眼坐在他右手桌子旁的女人。
He made one or two furtive phone calls. 他鬼鬼祟祟地打了一两个电话。
There was something furtive about his behaviour and I immediately felt suspicious. 他鬼鬼祟祟的，我马上觉得有些可疑。