Original: An autopsy, also known as a post-mortem examination, necropsy (particularly as to animals), autopsia cadaverum, or obduction, is a medical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present.
Simplified: An autopsy (also called post-mortem examination) is a medical examination of a corpse to find out what killed it (disease or injury).