Caprice.

I just learned an interesting bit of word history via Merriam-Webster’s delightfully discursive entry for caprice: Etymology borrowed from French, going back to Middle French, borrowed from Italian capriccio “whim, fancy,” earlier and medieval Tuscan caporiccio “bristling of the hair with fear, shiver of horror, shudder,” probably from capo “head” (going back to Vulgar Latin *capum, re-formation of Latin caput “head”) + riccio “hedgehog,” going back to Latin ērīcius — more at head entry 1, urchin Note: Italian capriccio has been a word of disputed origin, the principle issue being the peculiar semantic shift from “shiver of horror”—a meaning easily explicable from the compound’s bases “head” and “hedgehog”—to “whim, caprice,” and hence to various further senses. On these grounds M. Cortelazzo and P. Zolli (Dizionario etimologico della lingua italiana) consider the entire etymology uncertain, and speculate that two etyma of independent origin have somehow converged phonetically.…