police officer vs officer

police officer and officer both are nouns.

Word	Noun	Adjective	Verb	Adverb
police officer	Yes	No	No	No
officer	Yes	No	Yes	No

As nouns, police officer and officer are synonyms defined as:

police officer (noun)	officer (noun)
a member of a police force	a member of a police force
	someone who is appointed or elected to an office and who holds a position of trust
	any person in the armed services who holds a position of authority or command
	a person authorized to serve in a position of authority on a vessel

police officer (verb)	officer (verb)
	direct or command as an officer