Source : Webster's Revised Unabridged Dictionary (1913)

Abstruseness \Ab*struse"ness\, n.
   The quality of being abstruse; difficulty of apprehension.
   --Boyle.

Source : WordNet®

abstruseness
     n 1: the quality of being unclear or abstruse and hard to
          understand [syn: {obscureness}, {obscurity}, {reconditeness}]
          [ant: {clarity}]
     2: wisdom that is recondite and abstruse and profound; "the
        anthropologist was impressed by the reconditeness of the
        native proverbs" [syn: {reconditeness}, {abstrusity}, {profoundness},
         {profundity}]