The Collaborative International Dictionary of English v.0.48:

Undiscovered \Undiscovered\
   See discovered.

WordNet (r) 3.0 (2006):

undiscovered
    adj 1: not discovered; "with earth-based telescopes many stars
           remain undiscovered"
    2: not yet discovered; "undiscovered islands" [syn:
       undiscovered, unexplored]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "undiscovered":
   able, enigmatic, incalculable, incognizable, invisible, mysterious,
   puzzling, sealed, strange, unapparent, unapprehended,
   unascertained, unbeknown, uncharted, unclassified, undetected,
   undisclosed, undiscoverable, undivulged, unexplained, unexplored,
   unexposed, unfamiliar, unfathomed, unheard, unheard-of,
   unidentified, uninvestigated, unknowable, unknown, unperceived,
   unplumbed, unrevealed, unseen, unsolved, unspied, unsuspected,
   untouched, untraced, untracked, virgin