Source : Webster's Revised Unabridged Dictionary (1913)

Slyly \Sly"ly\, adv.
   In a sly manner; shrewdly; craftily.

         Honestly and slyly he it spent.          --Chaucer.

Source : WordNet®

slyly
     adv : in an artful manner; "he craftily arranged to be there when
           the decision was announced"; "had ever circumstances
           conspired so cunningly?" [syn: {craftily}, {cunningly},
            {foxily}, {knavishly}, {trickily}, {artfully}]