adjective

not known or seen or not meant to be known or seen by others. "how did you guess I'd got a secret plan?" синонимы: confidential, strictly confidential, top secret, classified, restricted, unrevealed, undisclosed, unpublished, untold, unknown, uncommunicated, behind someone's back, under wraps, unofficial, off the record, not to be made public, not to be disclosed, sub rosa, hush-hush, mum, hidden, concealed, camouflaged, disguised, unnoticeable, invisible, inconspicuous, clandestine, covert, undercover, underground, shrouded, conspiratorial, surreptitious, stealthy, cloak-and-dagger, hole-and-corner, closet, sneaky, sly, underhand, shifty, furtive, black, cryptic, encoded, coded, enciphered, mysterious, abstruse, recondite, arcane, esoteric, cabbalistic, secluded, private, sheltered, undisturbed, unfrequented, solitary, lonely, sequestered, out of the way, remote, isolated, off the beaten track, tucked away, cut-off

noun

something that is kept or meant to be kept unknown or unseen by others. "a state secret" синонимы: confidential matter, confidence, private affair, skeleton in the cupboard, skeleton in the closet