idiot
(id'ē-ŏt)
[L. idiota fr Gr. idiōtēs, private person, common man, unskilled or ignorant person]
In former medical and legal usage, a person with severe mental deficiency (mental age not over 3 years and IQ between 0 and 20).
SEE: idiocy; imbecile; mental retardation; moron.