WordNet (r) 3.0 (2006):

undisclosed
    adj 1: not made known [syn: undisclosed, unrevealed]

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "undisclosed":
   able, arcane, cabalistic, censored, classified, close, closed,
   concealed, cryptic, dark, enigmatic, esoteric, hermetic, hidden,
   hush-hush, incalculable, incognizable, invisible, latent,
   mysterious, occult, puzzling, restricted, sealed, secret,
   smothered, stifled, strange, suppressed, top secret, ulterior,
   unapparent, unapprehended, unascertained, unbeknown, unbreatheable,
   uncharted, unclassified, under security, under wraps, undetected,
   undisclosable, undiscoverable, undiscovered, undivulgable,
   undivulged, unexplained, unexplored, unexposed, unfamiliar,
   unfathomed, unheard, unheard-of, unidentified, uninvestigated,
   unknowable, unknown, unperceived, unplumbed, unrevealable,
   unrevealed, unseen, unsolved, unspied, unspoken, unsuspected,
   untellable, untold, untouched, untraced, untracked, unutterable,
   unuttered, unwhisperable, virgin