Definitions for "Idiot savant"
A person with gross mental retardation who nonetheless is capable of performing certain remarkable feats in sharply circumscribed intellectual areas, such as calendar calculation or puzzle solving.
An individual with a rare form of mental retardation, extraordinarily talented in one or a few limited areas of intellectual achievement; sometimes called autistic savant.
A child or adult who despite often (but not always) having a mental handicap has an extraordinary ability to perform mental calculations or demonstrate feats of knowledge, in many cases relating to numbers.