ranger

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A wanderer; a rover.
• noun A member of an armed troop employed in patrolling a specific region.
• noun A member of a group of US soldiers specially trained for making raids either on foot, in ground vehicles, or by airlift.
• noun A warden employed to maintain and protect a natural area, such as a forest or park.
• noun Chiefly British The keeper of a royal forest or park.

from The Century Dictionary.

• noun One who ranges, or roams, or roves about; especially, one engaged in ranging or going about for some specific purpose, as search or ward.
• noun Specifically In England, formerly, a sworn officer of a forest, appointed by the king's letters patent, whose business it was to walk through the forest, watch the deer, prevent trespasses, etc.; now, merely a government official connected with a royal forest or park.
• noun One of a body of regular or irregular troops, or other armed men, employed in ranging over a region, either for its protection or as marauders: as, the Texan rangers.
• noun One who roves for plunder; a robber.
• noun A dog that beats the ground.
• noun A sieve.
• noun A kind of fish. See the quotation.
• noun A kind of seal, probably the young bayseal.
• noun In some parts of the United States, a county officer who takes charge of stray animals. See the extract.
• noun A steer or horse raised on a cattlerange.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who ranges; a rover; sometimes, one who ranges for plunder; a roving robber.
• noun obsolete That which separates or arranges; specifically, a sieve.
• noun A dog that beats the ground in search of game.
• noun One of a body of mounted troops, formerly armed with short muskets, who range over the country, and often fight on foot.
• noun engraving The keeper of a public park or forest; formerly, a sworn officer of a forest, appointed by the king's letters patent, whose business was to walk through the forest, recover beasts that had strayed beyond its limits, watch the deer, present trespasses to the next court held for the forest, etc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun One who ranges; a rover.
• noun A keeper, guardian, or soldier who ranges over a region (generally of wilderness) to protect the area or enforce the law.
• noun obsolete That which separates or arranges; a sieve.
• noun A dog that beats the ground in search of game.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an official who is responsible for managing and protecting an area of forest
• noun a member of a military unit trained as shock troops for hit-and-run raids
• noun a member of the Texas state highway patrol; formerly a mounted lawman who maintained order on the frontier