1. Great difficulty or disruption of the ability to learn to read or to spell.
2. Difficulty in reading due to defects in the brain; specifically, word blindness.
3. An imprecise term concerning a condition in which an individual with normal vision is unable to interpret written language. 4. Impaired reading ability with a competence level below that expected on the basis of the individual’s level of intelligence, and in the presence of apparent normal vision and letter recognition and normal recognition of the meanings of pictures and objects.

A few clarifications regarding dyslexia

Two commonly held beliefs about dyslexia are that children with it see letters or words backward, and that the problem is linked to intelligence.

Both beliefs are considered to be wrong. The problem is a linguistic one, not a visual one, in dyslexia; and dyslexia in no way stems from any lack of intelligence. People with severe dyslexia can be and have been known to be of superior intelligence.

In fact, the effects of dyslexia vary from person to person. The only shared trait among people with dyslexia is that they read at levels significantly lower than is typical for people of their ages. Dyslexia is not the same as reading retardation which may reflect mental retardation or cultural deprivation.