What is the definition or description of: heat illness?

SPECTRUM OF DISORDER. Heat illness is a spectrum of disorder due to envoirenmental heat exposure.It can include heat syncope, heat cramps and heat exaustion more severe conditions are heat stroke, inwhich body temp goes over 105 degree f.Or 40.6 degreec due to envorenmental heat exposure and lac of thermo regulation.This is different than fever where there is physiological increase in temp of the body.