Autopsy is defined as
inspection and dissection of a body after death, as for determination of the cause of death; postmortem examination.
Necropsy is defined as
the examination of a body after death; autopsy.
In practice, it seems that "autopsy" is generally used when referring to the post-mortem examination of a human body, and "necropsy" refers to the examination of non-human bodies. I see no immediate evidence in the root words that would explain why we have this distinction, except perhaps for the "self" that αὐτός
refers to being used to describe post-mortem examination of humans specifically, leaving "necropsy" to mean examination of dead bodies in general.
That is all conjecture, however, and it seems like a stretch. So: where do these two separate words come from?
Best Answer
The word autopsy is older, and had the original meaning "to see with one's own eyes". The Oxford English Dictionary writes that it was first used in a now-obsolete sense in the 1600s:
Its current use only dates from the 1800s:
Necropsy is a much more recent coinage, and dates from the 1800s:
Note that in the example given, autopsy cadaverica and necropsy are synonymous. However, because an autopsy could have been the inspection of any body, it was used in the phrase "cadaverous autopsy" or "autopsia cadaverica". It seems that necropsy may have developed as a one-word term to describe the autopsy of a deceased person, though by the 1830s autopsy was being used on its own in its current sense:
However, it can be argued that the 1830 example was really referring to an autopsy of a body in general, who happened to be deceased (as there is qualification within the sentence which refers to death). Then, the first use of autopsy on its own without such qualification would be in the 1880s:
From this, I think that necropsy developed as a one-word synonym to cadaverous autopsy, and then over time autopsy came to be synonymous with necropsy.