10 Slang Words and Phrases Explained 1. Idiot Idiot originally comes from the Greek word Idiotes which was used to refer to a person who was a private individual – or more specifically, one who was so preoccupied with their own personal life that they would not take part in the democratic process. In the biblical sense, the word referred to an uneducated person. By the fourteenth century, it could also refer to a clown, a layman (non-religious), or an individual. Later, however, the Oxford English Dictionary gave it the following definition which has stuck: “A person so deficient in mental or intellectual faculty as to be incapable of ordinary acts of reasoning or rational conduct”. When IQ tests arrived, a person scoring less than 20 was regarded to have earned the “idiot’s score”.