/slaɪ; slaɪ/
adj (-er, -est)
1 (often derog 常作贬义) acting or done in a secret, often cunning and deceitful, way 狡猾的; 狡诈的
*a sly fellow, trick, ruse 狡诈的家伙、伎俩、计谋
* (joc 谑) You sly old devil! 你这个老奸巨猾的家伙!
* It was sly of you not to tell us you'd already met. 你们真坏, 已经见了面还瞒着我们.
2 [usu attrib 通常作定语] suggesting that one knows sth secret; knowing 会意的; 会心的
*a sly smile, look, etc 会心的一笑、表情等
* She cast a sly glance at her bridge partner. 她向桥牌搭挡使了个会意的眼色.
3 mischievous; playful 淘气的; 顽皮的
*play a sly trick on a friend 作弄朋友.
4 (idm 习语) on the `sly secretly 秘密地
*She must have been having lessons on the sly. 她准是暗地里一直在上课.

adj
[Date: 1200-1300; Language: Old Norse;Origin: slœgr]
someone who is sly cleverly deceives people in order to get what they want
= cunning
sly smile/glance/wink etc
a smile, look etc that shows you know something secret
　He leaned forward with a sly smile.
on the slyinformal
secretly, especially when you are doing something that you should not do
　They'd been seeing each other on the sly for months.
>slylyadv
>slynessn[U]