sly/slaI; slaI/adj 1 someone who is sly tries to get what they want by not being completely honest [ cunning ] 狡猾的﹐狡诈的2 showing that you know something that others do not know 诡秘的: a sly smile 诡秘的一笑3 on the slyinformal secretly【非正式】秘密地﹐偷偷地 —slyly adv