Meaning

noun a detachment used for security or reconnaissance

noun the activity of going around or through an area at regular intervals for security purposes

noun a group that goes through a region at regular intervals for the purpose of security

originFrom 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…

Etymology from Wiktionary, CC BY-SA 3.0