WILY

adj. shrewd, cunning, crafty, sly, artful, guileful, clever, foxy, vulpine, disingenuous, shifty, scheming, plotting, calculating, designing, sharp, canny, deceitful, deceiving, deceptive, treacherous, perfidious, false, double-dealing, dishonest, underhand(ed), tricky, smooth, slick, slippery, oily, unctuous, Scots and No. Eng. pawky, Colloq cagey, crooked, two-timing, Slang chiefly Brit fly Rats are wily and cunning, and have to be taken seriously