idiot savant

< /i dyoʊ saˈvɑ̃/. Psychiatry.

1. a mentally defective person with an exceptional skill or talent in a special field, as a highly developed ability to play music or to solve complex mathematical problems mentally at great speed.

noun plural idiots savants (ˈiːdjəʊ sæˈvɑ̃) or idiot savants

1. a person with learning difficulties who performs brilliantly at some specialized intellectual task, such as giving the day of the week for any calendar date past or present

n. pl. idiot savants

1. A mentally retarded person who exhibits genius in a highly specialized area, such as mathematics.