FURTIVE

[adjective] - (of people) behaving secretly so that other people do not notice them, or (of actions) done secretly and often quickly so that people do not noticeI saw him cast a furtive glance at the woman at the table to his right.He spent the afternoon making furtive phone calls whenever his boss was out of the office.There was something furtive about his behaviour and I immediately felt suspicious.He had the furtive air of someone on an embarrassing errand, like buying underwear for his mother.