List of surreptitious synonyms and surreptitious related words.
artful, back-door, backstairs, calculating, chiseling, clandestine, collusive, concealed, covert, covinous, crafty, cunning, deceitful, doggo, false, falsehearted, feline, finagling, fraudulent, furtive, guileful, hidden, hidden out, hidlings, hole-and-corner, hugger-mugger, hush-hush, in ambush, in hiding, in the wings, indirect, insidious, lurking, on the sly, on tiptoe, private, privy, prowling, pussyfoot, pussyfooted, quiet, scheming, secret, secretive, sharp, shifty, skulking, slinking, slinky, slippery, sly, sneaking, sneaky, stealing, stealthy, treacherous, trickish, tricky, two-faced, under cover, under-the-counter, under-the-table, undercover, underground, underhand, underhanded, unobtrusive, veiled, waiting concealed, wily