postmortem examination vs PM

postmortem examination and PM both are nouns.

Word	Noun	Adjective	Verb	Adverb
postmortem examination	Yes	No	No	No
PM	Yes	No	No	No

As nouns, postmortem examination and PM are synonyms defined as:

postmortem examination and PM: an examination and dissection of a dead body to determine cause of death or the changes produced by disease

Other synonyms of postmortem examination include autopsy, necropsy, post-mortem, post-mortem examination, postmortem.

postmortem examination (noun)	PM (noun)
an examination and dissection of a dead body to determine cause of death or the changes produced by disease	an examination and dissection of a dead body to determine cause of death or the changes produced by disease
	modulation of the phase of the carrier wave
	the person who holds the position of head of the government in the United Kingdom