Hyperpyrexia

[Sarah]

A condition of excessive fever; an elevation of temperature ina disease, in excess of the limit usually observed in that disease.

[Sarah]

It is another name for as what we call as fever. It is the inability of the body most especially of our hypotalamus to regulate our body temperature. Thus, our body gives off too much heat.
The hypotalamus is a part in the brain which is resposible for regulating our body temperature. It is called as a thermoregulatory organ in the brain.