sly

Clever or cunning, especially in the practice of deceit.

Stealthy or surreptitious.

Playfully mischievous.

(on the sly) In a way intended to escape notice.

. Cunning; skilful; shrewd.

Meanly artful; insidious; crafty.

Playfully artful; knowing; having an intentionally transparent artfulness.

Artfully and delicately wrought; cunning; ingenious.

Thin; fine; slight; slender.

Illicit: as, sly grog (liquor made in illicit stills).