The Collaborative International Dictionary of English v.0.48:

Autopsy \Au"top*sy\, n. [Gr. ?, fr. ? seen by one's self; ? self
   + ? seen: cf. F. autopsie. See Optic, a.]
   1. Personal observation or examination; seeing with one's own
      eyes; ocular view.
      [1913 Webster]

            By autopsy and experiment.            --Cudworth.
      [1913 Webster]

   2. (Med.) Dissection of a dead body, for the purpose of
      ascertaining the cause, seat, or nature of a disease; a
      post-mortem examination.
      [1913 Webster] Autoptic

WordNet (r) 3.0 (2006):

autopsy
    n 1: an examination and dissection of a dead body to determine
         cause of death or the changes produced by disease [syn:
         autopsy, necropsy, postmortem, post-mortem, PM,
         postmortem examination, post-mortem examination]
    v 1: perform an autopsy on a dead body; do a post-mortem