"Dys" means lack of function and "lexia" means words - thus "lack of function with words". Originally the term "Dyslexia" referred to a specific learning deficit that hindered a person's ability to read. More recently, however, it has been used as a general term referring to the broad category of language deficits such as those listed above.
Dyslexia is a language-based learning disability. Dyslexia refers to a cluster of symptoms, which result in people having difficulties with specific language skills, particularly reading. Students with dyslexia usually experience difficulties with other language skills such as spelling, writing, and pronouncing words. Dyslexia affects individuals throughout their lives; however, its impact can change at different stages in a person's life. It is referred to as a learning disability because dyslexia can make it very difficult for a student to succeed academically in the typical instructional environment, and in its more severe forms, will qualify a student for special education, special accommodations, or extra support services.
(Source: International Dyslexia Association)