idiot
UK[ˈɪd.i.ət]US[ˈɪd.i.ət]
n
A very stupid or foolish person
Etymology
The word 'idiot' entered English in the late 13th century from Old French 'idiote', meaning an uneducated or ignorant person. This derived from Latin 'idiota', a layman or ignorant person, which itself came from Greek 'idiōtēs' (ἰδιώτης), signifying a private person, a layman, or someone lacking professional skill, from 'idios' meaning 'one's own, private'. The semantic journey is from a neutral term for a private citizen (as opposed to one involved in public life) to a pejorative term for someone perceived as ignorant or lacking in knowledge, reflecting a classical view that valued public participation and specialized skill.
Analysis
The word 'idiot' is a simplex loanword from Greek via Latin and French. Its spelling and form are not productively composed of separable English morphemes.
Examples
He felt like a complete idiot for locking his keys in the car.
Don't be an idiot—look both ways before crossing the street.
The movie's plot relied on the main character being a loveable idiot.