From Greek 'idiotes' (private citizen who avoids public affairs) — in Athens, not participating in democracy made you an 'idiot.'
A stupid person.
From Greek 'idiotes,' meaning 'private person, one who does not participate in public affairs' — from 'idios' (one's own, private). In Athenian democracy, someone who didn't engage in politics was considered selfish and ignorant. Not participating in democracy made you an 'idiot.' Key roots: idios (Greek: "one's own, private, personal").