Dyslexia - Dyslexia is difficulty with language. Intelligence is not the
problem; the problem is language. People who are dyslexic may have
difficulty with reading, spelling, understanding language they hear, or
expressing themselves clearly in speaking or in writing. An unexpected
gap exists between their potential for learning and their school achievement.

Dyslexia – a language-based disability in which a person has trouble
understanding words, sentences or paragraphs; both oral and written language
are affected.

The International Dyslexia Association
http://www.interdys.org/