un•know•a•blePronunciation: (un-nō'u-bul), [key]
not knowable; incapable of being known or understood.
something that is unknowable.
2. the Unknowable,
the postulated reality lying behind all phenomena but not cognizable by any of the processes by which the mind cognizes phenomenal objects.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.