Noun
1. A common term for a person of low general intelligence.
2. A person of normal intelligence who is not giving enough thought to the job that they are currently doing.
3. A medical or psychological term meaning a person who has an intelligence quotient (IQ) between 70 and 80.
4. (humorous) Someone who is driving slower than you are, who is capable of driving much faster. Thus a person driving a piece of construction equipment like a backhoe at 15 miles per hour down a city street is not an idiot, while a person driving a modern car at 45 miles per hour on a fast expressway would be termed an idiot. Note: Comedian George Carlin proffered this definition.
5. (humorous) Someone whose picture you would like to see in this dictionary beside this word.
Examples
That idiot is standing there staring into space, blocking all of us from getting where we want to go.