The crossword solution for the term HEAD WARMER is FEVER. A FEVER is a medical condition in which the body temperature rises above the normal range. It is usually caused by an infection, such as the flu or a cold. Fevers can also be caused by other illnesses, such as cancer or autoimmune disorders. In some cases, a FEVER can be a sign of a more serious condition, so it is important to seek medical attention if a FEVER persists.