Other forms: patrols, patrolling, patrolled
A patrol is the regular round that police or soldiers walk or drive to keep watch over an area. On patrol, a routine patrol, send out a patrol.
The word covers the activity, the route and the group doing it, and the context sorts them out. On patrol takes no article and is the standard phrase. The verb is regular in meaning and awkward in spelling: patrolled, patrolling, with two l's, which is a common slip. Note patrol car and patrolman, both American, and that in Scouting a patrol is a small group of children within a troop, which is the only friendly use of the word.
1nounpatrolA regular round made to keep watch over an area.
“There is a patrol along the seafront every night.”
2verbregularlyTo go regularly round an area to keep watch.
“Two officers patrolled the estate for a fortnight.”
3noungroupThe group of people making such a round.
“The patrol was back by midnight.”
Too few real examples of this word to estimate which sense is commonest.
patrol is a watching round.
Old French patrouiller meant to paddle about in mud, from a root meaning a paw. A patrol was originally a tramp through the wet — a soldier's night round described from the boots up, which is a good deal more honest than the modern word sounds.
Proto-Indo-European
*(s)pent-
Proto-Germanic
*paþjaną
Frankish
*patta — paw, sole of the foot
Vulgar Latin
*patta — paw, foot
Old French
patrouille
French
patrouille
English, today
patrol
Built from
From French patrouille, from Old French patrouille, patouille (“a night-watch”) literally “a tramping about”, from patrouiller, patouiller, patoiller (“to paddle or pudder in water, dabble with the feet, begrime, besmear”), from patte, pate (“paw, foot of an animal”), from Vulgar Latin patta (“paw, foot”), from Frankish patta (“paw, sole of the foot”), from Proto-Germanic paþjaną, paþōną (“to walk, tread, go, step, pace”), possibly from Proto-Indo-European (s)pent-, (s)pat- (“path; to walk”), a variant of Proto-Indo-European pent-, pat- (“path; to go”); see find. Cognate with Dutch pad, patte (“paw”), Low German pedden (“to step, tread”), German patschen (“to splash, smack, dabble, waddle”), German Patsche (“a swatter, beater, paw, puddle, mire”). Related to pad, path.
Etymology from Wiktionary, CC BY-SA