patrol

1. 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. (countable, uncountable) · Four members of the squadron were on patrol.
2. 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. (countable, uncountable)
3. The guards who go the rounds for observation; a detachment whose duty it is to patrol. (countable, uncountable)
4. The largest division of officers within a police department or sheriff's office, whose assignment is to patrol and respond to calls for service. (countable, uncountable)
5. Any perambulation of a particular line or district to guard it; also, the people thus guarding. (countable, uncountable) · a customs patrol· a fire patrol
6. A unit of a troop, usually defined by certain ranks or age groups within the troop, and ideally comprised of six to eight members. (countable, uncountable)

Plural patrols