idiot-savant

id·i·ot-sa·vant

(ē-dē-ō' sah-vahn'),
A person of low general intelligence who possesses an unusual faculty for certain mental tasks of which most normal people are incapable.
Synonym(s): idiot-prodigy
[Fr.]

id·i·ot-sa·vant

(ē'dē-ō'sah-vawn[h]')
A person of low general intelligence who possesses an unusual facility in performing some mental tasks that most normal people cannot do (e.g., memorizing a telephone directory).
[Fr.]

idiot-savant

(ed-jo'sa-vant) [Fr., learned idiot]
An individual who is generally mentally retarded, but has the ability to do complicated tasks such as play instruments, recall dates, or accurately and rapidly perform mathematical calculations.
See: autism
References in periodicals archive ?
FORREST GUMP C4,10pm Tom Hanks stars as Gump, an idiot-savant at the memorable events of recent history, from the Vietnam War to the Watergate break-in.
Ably assisted by idiot-savant wine taster Ciaran Murtagh, the Reverend will change the way you feel about wine forever.
LOVELY old lady/gormless idiot-savant Ba-Nana Moon is off to the doctor's, raising the possibility of a brain scan - to see if there are any signs of it.
They're a pretty, weird bunch: a home-schooled idiot-savant, a little-Miss-Perfect, a walking anthology of lefty dogma.
There is a major bias in the CBO's idiot-savant assumption that all discretionary federal spending will remain unchanged for the next decade, aside from inflation adjustments.