Which term describes a high core body temperature leading to heat cramps and heat stroke?

The term that describes a high core body temperature leading to conditions such as heat cramps and heat stroke is hyperthermia. Hyperthermia occurs when the body absorbs more heat than it dissipates, resulting in an elevated body temperature which can lead to serious health complications like heat exhaustion or heat stroke. This condition can arise from prolonged exposure to high temperatures, rigorous exercise, or insufficient fluid intake, especially in hot weather.

In contrast, hypothermia refers to an abnormally low body temperature, typically resulting from prolonged exposure to cold environments, which is not relevant to the context of high core body temperature. Vasodilation is a physiological process where blood vessels widen, typically to help cool the body, but it is not a condition that leads to heat-related illnesses. Dehydration can contribute to increased body temperature but describes a state of fluid deficiency rather than the condition of having a high body temperature itself. Thus, hyperthermia is the most appropriate and specific term to describe the situation described in the question.