Idiot savant means: The idiot savant. See: Autistic genius. As it is less offensive and more specific, the term “autistic genius” is preferable to “idiot skilled”.
(in Medical Dictionary)

What else does Idiot savant mean?

Person with cognitive impairment or developmental disability, such mental retardation, autism or other forms of mental illness, that exhibits exceptional ability in highly-specialized areas such as memorization or arithmetic.
(in Merlin Dictionary)