The DICT Development Group

  114 Moby Thesaurus words for "hidden":
     abstract, abstruse, arcane, beclouded, behind the curtain,
     behind the scenes, between the lines, blind, buried, cabalistic,
     camouflaged, censored, classified, close, closed, clouded,
     concealed, covered, covert, cryptic, dark, deep, delitescent,
     disguised, dormant, eclipsed, enigmatic, esoteric, guarded,
     hermetic, hibernating, hid, hush-hush, imperceptible, in a cloud,
     in a fog, in eclipse, in purdah, in the wings, incommunicado,
     indiscernible, insensible, invisible, latent, lurking, muffled,
     mysterious, mystic, obfuscated, obscure, obscured, occult,
     out of sight, possible, potential, private, privy, profound,
     recondite, restricted, secluded, secluse, secret, sequestered,
     shrouded, sightless, sleeping, smothered, stifled, submerged,
     suppressed, top secret, transcendental, ulterior, unapparent,
     unbeheld, unbeholdable, unbreatheable, under an eclipse,
     under cover, under house arrest, under security, under the surface,
     under wraps, underground, underlying, undiscernible, undisclosable,
     undisclosed, undivulgable, undivulged, unknown, unmanifested,
     unnoticed, unobserved, unperceivable, unperceived, unrealized,
     unrevealable, unrevealed, unseeable, unseen, unspoken, untellable,
     untold, unutterable, unuttered, unviewed, unwhisperable,
     unwitnessed, veiled, viewless, virtual, wrapped in clouds