Numpty.

1. A stupid person; an idiot.
2. A bumbling fool or one who is intellectually challenged.
3. Someone who (sometimes unwittingly) demonstrates a lack of knowledge or misconception of a subject or situation to the amusement of others.
4. A reckless, absent minded or unwise person.
5. A good humoured admonition, a term of endearment.

Originally Scots dialect.

In 2007 numpty was voted Scotland’s favourite word.