adj.
(slyer, slyest)
- having a cunning and deceitful nature.
- (of a remark, glance, or expression) insinuating.
- (of an action) surreptitious.
Phrase
- on the sly
in a surreptitious fashion.
Derivative
- slyly
(also slily)
adv.
- slyness n.
Etymology
ME (also in the sense ‘dexterous’): from ON slœgr ‘cunning’.