The word "idiot" originally meant "a person who is not interested in politics"

Now the word "idiot" two meanings: the most common - offensive, the second - medical designating the person with the most profound degree of mental retardation.

However, the Greek word originally meant Idiōtēs only a "person who is not interested in politics." Because of the negative connotations of the word "idiot" gradually took the meaning that is familiar to us today.

via factroom.ru