p.m. vs postmortally

p.m.

adv
  • after death 

  • after noon (used after a time to indicate it is between noon and midnight, i.e., in the afternoon, evening or night as opposed to the morning) 

postmortally

adv
  • Synonym of post mortem 

How often have the words p.m. and postmortally occurred in a corpus of books? (source: Google Ngram Viewer )