"Policeman" in French is said as:
_"Policier" (masculine) or
_"Policière" (feminine equivalent, but considered as "incorrect" by language purists)
But the French also have what they call "Gendarmerie" ("Gendarme" would be the word then) which is a military force that mainly maintains order in rural regions of France as well as city suburbs, whereas "Police"officers would rather work in urban areas only. There are other fundamental differences between the two institutions, but they can both be a translation to "policeman".