Mayhem
early 16th century: from Old French mayhem (see maim). The sense ‘disorder’ (originally US) dates from the late 19th century.
wiktionary
From Middle English mayme, mahaime, from Anglo-Norman mahaim(“mutilation”), from Old French mahaign(“bodily harm, loss of limb”), from Proto-Germanic *maidijaną(“to cripple, injure”) (compare Middle High German meidem, meiden(“ gelding”), Old Norse meiða(“to injure”), Gothic 𐌼𐌰𐌹𐌳𐌾𐌰𐌽( maidjan, “to alter, falsify”)), [1] from Proto-Indo-European *mey-(“to change”). More at mad. The original meaning referred to the crime of maiming, the other senses derived from this.
Another possible etymology derives the Old French from Provençal maganhar, composed of mal(“evil”) and ganhar(“to obtain, receive”) (compare with Spanish ganar and Italian gavagnare and guadagnare), so literally "to obtain, receive something evil).
Meaning #1 may have arisen by popular misunderstanding of the common journalese expression " rioting and mayhem".
etymonline
mayhem (n.)
late 15c., "the violent doing of a bodily hurt to another person," from Anglo-French maihem (13c.), from Old French mahaigne "injury, wrong, a hurt, harm, damage;" related to mahaignier "to injure, wound, mutilate, cripple" (see maim). Originally, in law, the crime of maiming a person "to make him less able to defend himself or annoy his adversary" [OED]. By 19c. it was being used generally of any sort of violent disorder or needless or willful damage or violence.
