*patrol*

v. t. To go the rounds of, as a sentry, guard, or policeman; as, to patrol a frontier; to patrol a beat. [ 1913 Webster ]

n. [ F. patrouille, OF. patouille. See Patrol, v. i. ] 1. (Mil.) (a) A going of the rounds along the chain of sentinels and between the posts, by a guard, usually consisting of three or four men, to insure greater security from attacks on the outposts. (b) A movement, by a small body of troops beyond the line of outposts, to explore the country and gain intelligence of the enemy's whereabouts. (c) The guard or men who go the rounds for observation; a detachment whose duty it is to patrol. [ 1913 Webster ]

2. Any perambulation of a particular line or district to guard it; also, the men thus guarding; as, a customs patrol; a fire patrol. [ 1913 Webster ]

In France there is an army of patrols to secure her fiscal regulations. A. Hamilton. [ 1913 Webster ]

3. See Boy Scout. [ Webster 1913 Suppl. ]

n. & v. See Patrol, n. & v. [ 1913 Webster ]

n. An individual or a member of a group that patrols an area. [ WordNet 1.5 ]

n. The activity of going around or through an area at regular intervals for security purposes.
Syn. -- patrol. [ WordNet 1.5 ]

n.; pl. Patrolmen One who patrols; a watchman; especially, a policeman who patrols a particular precinct of a town or city. [ 1913 Webster ]