Source : Webster's Revised Unabridged Dictionary (1913)

Incomprehension \In*com`pre*hen"sion\, n.
   Want of comprehension or understanding. ``These mazes and
   incomprehensions.'' --Bacon.

Source : WordNet®

incomprehension
     n : an inability to understand; "his incomprehension of the
         consequences" [ant: {comprehension}]