[1] : The Collaborative International Dictionary of English v.0.48

undiscoverable \undiscoverable\
   see discoverable.
see also:
discoverable 

[2] : WordNet (r) 2.0

undiscoverable
     adj : not able to be ascertained; resisting discovery syn: unascertainable
see also:
unascertainable 

[3] : Moby Thesaurus II by Grady Ward, 1.0

52 moby thesaurus words for "undiscoverable":
   able, beyond reach, closed forever to, closed to, enigmatic,
   impenetrable, impervious, inaccessible, incalculable, incognizable,
   lost to, mysterious, out of reach, puzzling, sealed, strange,
   un-come-at-able, unaccessible, unapparent, unapprehended,
   unapproachable, unascertained, unattainable, unavailable,
   unbeknown, uncharted, unclassified, undisclosed, undiscovered,
   undivulged, unexplained, unexplored, unexposed, unfamiliar,
   unfathomed, ungettable, unheard, unheard-of, unidentified,
   uninvestigated, unknowable, unknown, unobtainable, unperceived,
   unplumbed, unprocurable, unreachable, unrevealed, unsecurable,
   unsuspected, untouched, virgin

Undiscoverable >> U Words
Undiscoverable, definition of term: Undiscoverable
undiscoverable_pag1.html