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algor mortis

n. The reduction in body temperature following death.

Wikipedia
Algor mortis

Algor mortis ( Latin: algor—coldness; mortis—of death), the second stage of death, is the change in body temperature post mortem, until the ambient temperature is matched. This is generally a steady decline, although if the ambient temperature is above the body temperature (such as in a desert), the change in temperature will be positive, as the (relatively) cooler body acclimates to the warmer environment. External factors can have a significant influence.