1) Arch quality 2) Artful quality 3) Astuteness 4) Craft 5) Craftiness 6) Crafty nemesis of Al Capone 7) Cunning 8) Cunning quality 9) Duplicity 10) Foxiness 11) Foxy attribute 12) Foxy characteristic 13) Foxy quality 14) Foxy trait 15) Guile 16) Perspicaciousness 17) Perspicacity 18) Shrewdness 19) Trickery 1) Craft 2) Craftiness 3) Cunning 4) Foxiness 5) Furtiveness 6) Guile 7) Secretiveness 8) Wiliness 
• (n.) The quality or state of being sly.
Sly'ness noun The quality or state of being sly.