all fours, back-door, backstairs, clandestine, covert, cowering, crawl, crawling, creep, creeping, cringing, deep-rooted, deep-seated, devious, doggo, duplicitous, feline, furtive, guileful, gumshoeing, gut, hidden, hidden out, hidlings, hole-and-corner, hugger-mugger, in ambush, in hiding, in the wings, indirect, inherent, innate, intuitive, lingering, lurking, nagging, niggling, nightwalking, on tiptoe, padding, persistent, private, privy, prowling, pussyfoot, pussyfooted, pussyfooting, quailing, quiet, scrabble, scramble, secret, shifty, sidling, skulking, slinking, slinky, sly, snaking, sneaky, stealing, stealthy, suppressed, surreptitious, tippytoe, tiptoe, tiptoeing, undeclared, under-the-counter, under-the-table, under cover, undercover, underground, underhand, underhanded, undisclosed, undivulged, unexpressed, unobtrusive, unrevealed, unvoiced, waiting concealed, worming, worrisome, worrying