behaviour that is clever in order to deceive people and get what you want

The prosecution appealed to popular stereotypes about the slyness of women.

He uses all his slyness to provoke a confrontation with his son. 他动用了所有的狡猾手段来挑起与儿子的对抗。

behaviour that suggests that you know secrets

Girls she'd been to school with said, "Welcome," and some had slyness in their smiles. 和她一起上学的女孩说：“欢迎你，”其中有些人带着狡黠的微笑。