An abnormally large forehead.

a large forehead

When some one has an extremely large forehead.

A grossly immense forehead, capable of reflecting enough sunlight to blind someone, or play movies onto.

A "four-head" is when you can only fit four fingers between your eyebrows and your hairline. You have a fivehead if you have such an abnormally large forehead that you can fit all five fingers.

A person who doesn't quite fit the category of a forehead. Usually is as big as the span of five fingers.

A person with a large forehead, that could fit five or more fingers.