Source : Webster's Revised Unabridged Dictionary (1913)

Knavishly \Knav"ish*ly\, adv.
   1. In a knavish manner; dishonestly; fraudulently. --Holland.

   2. Mischievously; waggishly; roguishly. ``Knavishly witty.''
      --Gayton.

Source : WordNet®

knavishly
     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}, {slyly}, {trickily}, {artfully}]