a member of the Texas state highway patrol; formerly a mounted lawman who maintained order on the frontier
"The historic documentary depicted an old cowboy ranger riding his horse through the dusty frontier towns to keep the peace."
an official who is responsible for managing and protecting an area of forest
"The ranger patrolled the forest to ensure that no illegal logging took place."
One who ranges; a rover.
"The team celebrated their victory when the star player was traded to the Rangers."
A player on any of various teams called Rangers, such as the Texas Rangers (in baseball) or the New York Rangers (in ice hockey).
In plain English: A ranger is an official who works outdoors to protect nature and keep public areas safe for visitors.
"The park ranger guided us through the trail and explained how to stay safe from bears."
To work as a ranger.
"She decided to apply to become a park ranger after graduating from college."
A surname.
"The famous explorer, John Ranger, published his memoirs last year."
The word ranger comes from the verb range, which originally meant to move freely over an area. By adding the suffix -er to indicate someone who performs that action, it created a term for a person who patrols or moves through a specific territory.