Meaning

noun a person of subnormal intelligence

originFrom Middle English idiote, ydiote, from Old French idiote (later idiot), from Latin idiota, from Ancient Greek ἰδιώτης (idiṓtēs, “a private citizen, one who has no professional knowledge, layman”), from ἴδιος (ídios, “one's own, pertaining to oneself, private”). Doublet of idiota. By surface analysis, idi- + -ot.

Etymology from Wiktionary, CC BY-SA 3.0