rang·er 
(rānjər)
(rānjər)n.
1. A wanderer; a rover.
2. A member of an armed troop employed in patrolling a specific region.
3. Ranger A member of a group of US soldiers specially trained for making raids either on foot, in ground vehicles, or by airlift.
4.
a. An officer employed to maintain and protect a publicly owned site or tract of land, such as a national forest or a state park.
b. Chiefly British The keeper of a royal forest or park.