Source : Webster's Revised Unabridged Dictionary (1913)

Holocryptic \Hol`o*cryp"tic\, a. [Holo-+ Gr. ? to conceal.]
   Wholly or completely concealing; incapable of being
   deciphered.

   {Holocryptic cipher}, a cipher so constructed as to afford no
      clew to its meaning to one ignorant of the key.