The forehead of humans is the flat space of skin above the eyes, between the eyebrows and where your hair starts to grow. It exists to make room for the brain inside the skull.
A doctor or nurse will often touch someone's forehead to check whether or not they have a fever. This is because of the many blood vessels in the head and face.
In ancient Greece individuals with large foreheads were classified as intellectual because of their incredibly large "brain". Nowadays this is not the case.
According to the OED Forehead can be pronounced either 'forhed' or 'forrid'.