Klein's Comprehensive Etymological Dict. of the English Lang. (1971) havoc: from, Old French havot, seizure, plunder, faire havot, 'to take hold of'. Related to haver, 'to seize, to grasp to grab,' hef, 'a hook,' havee, 'a handful.'; of Teutonic origin. Cp. Old High German haben, 'to hold, have', heffan, 'raise, heave.' Jonathon Green