patrolman

noun, plural pa·trol·men.

1. a police officer who is assigned to patrol a specific district, route, etc.
2. a person who patrols.

noun plural -men

1. mainly US a man, esp a policeman, who patrols a certain area
2. British a man employed to patrol an area to help motorists in difficulty

n.“police constable on a particular beat,” 1841, from patrol (n.) + man (n.).