So slow, deliberate, and secret as to escape observation
The records showed furtive criminal activity.
She gave a furtive look at the deserted shops on the opposite side of the road.
He watched her furtive glances, waiting for the signal to approach.
This blatancy factor, embedded in UFO waves, alternates with periods in which UFO behavior seems more subtle, even furtive.
His furtive eyes and jutting chin capture the two sides of the man: a craven, clever bully.