Chead

A person with an abnormally large head, particularly when the person's head is wider than its height. A good rule of thumb is roughly the proportion of Arnold's head from "Hey! Arnold".

This word is slang for "chode-head", because of the width to length ratio.

"Hey dude, have you seen how wide that girl's head is?"
"Really? How wide was her head?"
"Dude, like she has a chead."
"Wow, that's wide."