E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Harum Scarum.
A hare-brained person who scares quiet folk. Some derive it from the French clameur de Haro (hue and cry), as if the madcap was one against whom the hue-and-cry is raised; but probably it is simply a jingle word having allusion to the “madness of a March hare,” and the “scaring” of honest folks from their proprieties.
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