n (military) The guard or men who go the rounds for observation; a detachment whose duty it is to patrol.
n (military) 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.
n (military) 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.
n Any perambulation of a particular line or district to guard it; also, the men thus guarding; as, a customs patrol; a fire patrol.
n (context|Scouting) A unit of a troop, typically composed of around eight boys.
v (intransitive) To go the rounds along a chain of sentinels; to traverse a police district or beat.
v (transitive) To go the rounds of, as a sentry, guard, or policeman; as, to patrol a frontier; to patrol a beat.