Synonyms and related words :
arcane, cabalistic, classified, close, closed, concealed, cryptic, dark, enigmatic, esoteric, hermetic, hidden, hush-hush, latent, mysterious, occult, restricted, secret, smothered, stifled, suppressed, top secret, ulterior, unbreatheable, under security, under wraps, undisclosable, undisclosed, undivulgable, undivulged, unrevealable, unrevealed, unspoken, untellable, untold, unutterable, unuttered, unwhisperable,