Idiot means fool, goofy. From the Greek "idiots" which means "lay person, without professional skills", as opposed to those who developed some specialized work. In the original meaning, idiot literally designated the private citizen, someone who was dedicated only to matters individuals in opposition to the citizen who occupied some public office or participated in public order matters.
The term evolved in a derogatory way to characterize an ignorant, simple, uneducated person. Popularly, an idiot is a silly, imbecile, lacking in intelligence and common sense individual. Idiocy is the product of the idiot.
In Psychiatry, the idiot is one who suffers from "idiocy", which is the diagnosis attributed to the mentally deficient individual, with an advanced degree of mental retardation, linked to brain damage. In the state of profound idiocy, the bearer of this pathology has his vital capacities reduced in a coma-like state.
The Idiot (book)
The idiot is the title of a novel by Russian writer Fyodor Dostoevsky. The book tells the story of a man with epilepsy, a good and humanistic man who, because of his attitudes of great compassion, is seen by others as an idiot.