undiscoverable (adj.)

• able
• enigmatic
• impenetrable
• impervious
• inaccessible
• incalculable
• incognizable
• mysterious
• puzzling
• sealed
• strange
• un-come-at-able
• unaccessible
• unapparent
• unapproachable
• unattainable
• unavailable
• unbeknown
• uncharted
• unclassified
• undisclosed
• undiscovered
• unexplained
• unexplored
• unfamiliar
• unfathomed
• unheard
• unheard-of
• unidentified
• unknowable
• unknown
• unobtainable
• unperceived
• unplumbed
• unprocurable
• unreachable
• unrevealed
• unsuspected
• untouched
• virgin