Some everyday ones are police officer, officer of the law, detective and (at least in Britain) constable.
There are many less formal ones, which vary from place to place. British ones include Bobby, Peeler, copper and a peculiarly Liverpudlian one, Rozzer.
Official is another word for officer. Additional synonyms include deputy, executive, lawman, officeholder, policeman and representative.
Cop
They are synonyms.
Synonyms
policeman's
Relative and kin are synonyms.
A Policeman is a Police Officer that is male.
What degree do you need to be a policeman?
A posse of policeman
They are synonyms.
synonyms
The synonyms for upon is on