Synonyms to on the sly

guilefully, artfully, astutely, cagily, cannily, cleverly, cunningly, deceitfully, foxily, fraudulently, furtively, indirectly, insidiously, knowingly, shiftily, shrewdly, slick, slyly, smoothly, subtilely, subtlely, surreptitiously, treacherously, trickily, underhandedly, warily, wilily, incognito, anonym, anonymity, anonymous, anonymousness, camouflage, camouflaged, closed meeting, closet, concealed, confidentiality, confidentialness, cryptonymic, cryptonymous, disguise, disguised, domino, executive session, false colors, false face, false front, guisard, guiser, impersonator, in disguise, incog, incognita, inmost, innermost, innominate, interior, intimate, inward, isolated, isolation, mask, masked, masker, masque, masquerade, masquerader, masquerading, mummer, mummery, nameless, namelessness, personal, privacy, private, private conference, privy, protective coloration, retired, retirement, secluded, seclusion, secretly, sequestered, sequestration, smoke screen, unacknowledged, undefined, under cover, undesignated, unidentified, unknown, unnamed, unrecognizable, unrecognized, uns