According to WebMD, a high body temperature for an adult is an oral temperature over 100 degrees Fahrenheit or a rectal or ear temperature over 101 degrees Fahrenheit. A high body temperature is referred to as a fever.
While most people believe that a "normal" body temperature is 98.6 degrees, an individual's "normal" body temperature can be a degree higher or lower than that. Moreover, body temperature is subject to variation during the day based on activity levels and hormone levels.
Body temperature of increases in response to infections. Certain medicines also cause fevers. Severe injury or trauma can lead to elevated body temperatures as well, and some medical conditions, such as hyperthyroidism, certain cancers and arthritis, can cause a fevers