patrolyoudaoicibaDictYouDict[patrol 词源字典]
patrol: [17] What is now a reasonably dignified term began life as a colloquialism meaning ‘paddle about in mud’. English acquired the word via German from French patrouiller, which originally denoted ‘tramp around through the mud of a military camp – when doing guard duty, for instance’. This was an alteration of Old French patouiller ‘walk or trample in mud’, a verb based on the noun patte ‘paw’.

Other English words which trace their history back to patte are patois [17] (which developed via the Old French verb patoier ‘trample on’, hence ‘treat roughly’, and originally meant ‘rough speech’) and patten ‘wooden shoe’ [14].
=> patois, patten[patrol etymology, patrol origin, 英语词源]
patrol (n.)youdaoicibaDictYouDict
1660s, "action of going the rounds" (of a military camp, etc.), from French patrouille "a night watch" (1530s), from patrouiller "go the rounds to watch or guard," originally "tramp through the mud," probably soldiers' slang, from Old French patouiller "paddle in water," probably from pate "paw, foot" (see patten). Compare paddlefoot, World War II U.S. Army slang for "infantry soldier." Meaning "those who go on a patrol" is from 1660s. Sense of "detachment of soldiers sent out to scout the countryside, the enemy, etc." is attested from 1702.
patrol (v.)youdaoicibaDictYouDict
1690s, from patrol (n.) and in part from French patrouiller. Related: Patrolled; patrolling.