stealthy

1 given to acting in secret and to concealing one's intentions cats are among the stealthiest of stalkers Synonyms furtive, shady, shifty, slippery, sly, sneaking, sneakyRelated Words artful, crafty, cunning, devious, foxy, guileful, slick, wily; close, closemouthed, reticent, secretive; clandestine, covert, dark; deceitful, deceiving, deceptive, devious, duplicitous, trickish, tricky, underhand, underhanded; cheating, crooked, defrauding, dishonest, dissembling, double-dealing, knavish, two-faced; lying, mendacious, untrustworthy, untruthful; insidious, perfidious, serpentine, treacherousNear Antonyms aboveboard, forthright, plainspoken, straightforward; candid, direct, foursquare, frank, open, plain; honest, trustworthy, truthful

2 undertaken or done so as to escape being observed or known by others constantly harassed the enemy with stealthy raids Synonyms backstairs, behind-the-scenes, clandestine, covert, furtive, hole-and-corner, hugger-mugger, hush-hush, private, privy, sneak, sneaking, sneaky, stealth, secret, surreptitious, undercover, underground, underhand, underhandedRelated Words back-channel, closed-door, off-the-books, off-the-record; classified, confidential, restricted, top secret, undisclosed; concealed, hidden, secreted, subterranean, unadvertised, unexposedNear Antonyms acknowledged, avowed; aboveboard, straightforward, unconcealed, undisguised; unclassified, unrestricted; clear, evident, manifest, obvious, patent, plainAntonyms open, overt, public