patrol

Concise Oxford English Dictionary © 2008 Oxford University Press:
patrol/pəˈtrəʊl/

▶noun

• 1 a person or group sent to keep watch over an area, especially a detachment of guards or police.

  ■ a unit of six to eight Scouts or Guides forming part of a troop.

• 2 the action of patrolling an area.

• 3 an expedition to carry out reconnaissance.

  ■ a routine operational voyage of a ship or aircraft.

▶verb (patrols, patrolling, patrolled) keep watch over (an area) by regularly walking or travelling around it.

– derivatives
patroller noun.

– origin C17: from Ger. Patrolle, from Fr. patrouille, from patrouiller ‘paddle in mud’, from patte ‘paw’ + dial. (gad)rouille ‘dirty water’.