Hyperlexia

Hyperlexia is a precocious early reading ability that manifests in some Autistic children and occasionally in non-Autistic children as well.

Hyperlexic children develop reading skills considerably earlier than the majority of children, and continue throughout childhood to demonstrate reading skills far in advance of the average for their age.

Hyperlexic children are sometimes (though not always) slower than average in acquiring spoken language skills, particularly the pragmatics of social conversation. Often the early speech of hyperlexic children sounds more like passages of text from books than like conventional dialogue. Hans Asperger, who did some of the earliest pioneering work in studying Autism, described some of the children he worked with as sounding like "little professors."

Perhaps one never really outgrows hyperlexia. This lexicon you're reading right now certainly seems to be the product of a gleefully hyperlexic mind - thus the title, Hyperlexicon.