Source : Webster's Revised Unabridged Dictionary (1913)

Alexia \A*lex"i*a\, n. [NL.; a- not + Gr. ? speech, fr. ? to
   speak, confused with L. legere to read.] (Med.)
   (a) As used by some, inability to read aloud, due to brain
       disease.
   (b) More commonly, inability, due to brain disease, to
       understand written or printed symbols although they can
       be seen, as in case of word blindness.

Source : WordNet®

alexia
     n : inability to perceive written words [syn: {visual aphasia},
         {word blindness}]