Thesaurus

(n) : 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; 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

(v) : to go the rounds along a chain of sentinels; to traverse a police district or beat; to go the rounds of, as a sentry, guard, or policeman; as, to patrol a frontier; to patrol a beat