Numskull (noun)

A stupid or foolish person.

Origin:

Of uncertain origin, first recorded in the late 16th century. it may have derived from the word "numbskull", which was used to describe a person who was thought to have a thick skull or a dull mind.

Examples:

1. He"s such a numskull, he can"t even tie his own shoelaces.
2. Don"t trust him, he"s a numskull and he"ll only make things worse.
3. I can"t believe I"m stuck working with this numskull.
4. The numskull didn't understand the instructions.
5. I'm not going to explain it to you again, you numskull.