The handwriting clearly belonged to an unstable, conniving, furtive, shallow creep.
Sanger turned birth control from a furtive, underground pursuit into an international movement.
Our prayer and spiritual life was furtive even though we were all drawing on it to make it through rough and trying days.
late 15c. (implied in furtively), from French furtif, from Latin furtivus "stolen, hidden, secret," from furtum "theft, robbery," from fur (genitive furis) "thief," probably from PIE *bhor-, from root *bher- (1) "to carry" (see infer). Related: Furtiveness.