The NIH definition of Dyslexia |
A specific learning disability that is neurological in origin.It is characterized by difficulties with accurate and/or fluent word recognition, and by poor spelling and decoding abilities. These difficulties result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge.
International Dyslexia Association definition of Dyslexia | Dyslexia is a neurologically-based, often familial, disorder which interferes with the acquisition and processing of language. Varying in degrees of severity, it is manifested by difficulties in receptive and expressive language, including phonological processing, in reading, writing, spelling, handwriting, and sometimes in arithmetic.
Dyslexia is not the result of lack of motivation, sensory impairment, inadequate instructional or environmental opportunities, or other limiting conditions, but may occur together with these conditions.
Although dyslexia is life-long, individuals with dyslexia frequently respond successfully to timely and appropriate intervention.