The Collaborative International Dictionary of English v.0.48:

Incomprehension \In*com`pre*hen"sion\, n.
   Lack of comprehension or understanding. "These mazes and
   incomprehensions." --Bacon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

incomprehension
    n 1: an inability to understand; "his incomprehension of the
         consequences" [ant: comprehension]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "incomprehension":
   blindness, deafness, dim-sightedness, imperceptiveness,
   impercipience, incognizance, insensibility, mindlessness,
   nearsightedness, nonrealization, nonrecognition, nonunderstanding,
   purblindness, shortsightedness, unapprehendingness, unawareness,
   unconsciousness, undiscerningness, unmindfulness, unperceptiveness,
   unwittingness