A cadaver is a dead human body used in scientific or medical research. If you are dead, you are a corpse, but if Dr. Frankenstein robs your grave so he can use your body for research, you become a cadaver. Umm... congratulations?
Cadaver comes from the Latin verb, cadere, which means “to fall." Its English origins refer to soldiers who died in battle, i.e. the fallen. Dissection of a cadaver is a major rite of passage for medical school students––some have been known to run from the room and throw up — though most surprise themselves.