Machiavellian, Machiavellic, acute, arch, artful, astute, back-door, backstairs, cagey, canny, catlike, catty, clandestine, clever, closet, covert, crafty, cunning, cute, deceitful, deep, deep-laid, designing, diplomatic, doggo, feline, foxy, furtive, guileful, hidden out, hidlings, hole-and-corner, hugger-mugger, hush-hush, in ambush, in hiding, in the wings, ingenious, insidious, inventive, knowing, lurking, noiseless, on tiptoe, pawky, politic, privy, prowling, pussyfoot, pussyfooted, quiet, ready, resourceful, scheming, secret, secretive, serpentine, sharp, shifty, shrewd, silent, skulking, slick, slinking, slinky, slippery, sly, smooth, snaky, sneak, sneaking, sneaky, sophistical, stealing, stealthful, strategic, subtile, subtle, supple, surreptitious, tactical, trickish, tricksy, tricky, under cover, under-the-counter, under-the-table, undercover, underground, underhand, underhanded, unobtrusive, vulpine, waiting concealed, wary, wily