idiot savant

UK: French: /ˈiːdjəʊ sæˈvɑ̃/, English: /ˈɪdɪət ˈsævənt/

US: (id′ē ət sa vänt′, sə vant′, sav′ənt; Fr. ē dyō sa vän′)

Inflections of 'idiot savant' (n): npl: idiot savants

WordReference Random House Unabridged Dictionary of American English © 2025

id•i•ot sa•vant  (id′ē ət sa vänt′, sə vant′, sav′ənt; Fr. ē dyō sa vän′), pl. id•i•ot sa•vants, Fr. id•i•ots sa•vants (ē dyō sa vän′). [Psychiatry.]

1. Psychiatry 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.

• French: literally, learned idiot
• 1925–30

Collins Concise English Dictionary © HarperCollins Publishers::

idiot savant / ˈiːdjəʊ sæˈvɑ̃ ˈɪdɪət ˈsævənt/ noun (idiots savants / ˈiːdjəʊ sæˈvɑ̃/, idiot savants)

1. 
   an old-fashioned term for savant2

Etymology: 19th Century: from French: knowledgeable idiot