Inherited from Latin ēricius, from Proto-Indo-European *ǵʰḗr (“to bristle”). The expected normal result would have been *ariț, and explanations for the current form include an intermediate Vulgar Latin *ērix, ēricis or alternatively *ēriciō, ēriciōnem, in which case it would be regressively derived from a hypothetical Romanian *ariciune (compare French hérisson, Catalan eriçó, Romansch erizun). It may also have simply been a change in the suffix. The change also seems to have affected a form of the Aromanian equivalent. Compare Italian riccio, Sardinian rizzu.