The Collaborative International Dictionary of English v.0.48:

Post-mortem \Post-mor"tem\, a. [L., after death.]
   After death; as, post-mortem rigidity.
   [1913 Webster]

   Post-mortem examination (Med.), an examination of the body
      made after the death of the patient; an autopsy.
      [1913 Webster]

WordNet (r) 3.0 (2006):

post-mortem
    n 1: discussion of an event after it has occurred [syn:
         postmortem, post-mortem]
    2: 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]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "postmortem":
   autopsy, canvass, check, check out, check over, check up on,
   coroner, examine, give an examination, go over, inquest, inspect,
   look at, look over, medical examiner, monitor, mortality committee,
   necropsy, necroscopy, observe, overhaul, overlook, pass over,
   pass under review, peer at, peruse, pore over, post, post-obit,
   posthumous, postmortal, postmortem examination, postmortuary,
   postmundane, postobituary, review, run over, scan, scrutinize,
   set an examination, size, size up, study, survey, take stock of,
   take the measure