From Proto-Italic *arjēts ~ *erjēts (compare Umbrian 𐌄𐌓𐌉𐌄𐌕𐌖 (erietu)), perhaps from Proto-Indo-European *h₁r-i-(e)t- (“young domesticated caprine”). Cognate with Old Irish heirp, erb (“kid”), Ancient Greek ἔριφος (ériphos, “kid”), displaying a different suffix, and perhaps Old Armenian որոջ (oroǰ, “lamb”), երինջ (erinǰ, “heifer”). However, as the cognates demonstrate, this has the characteristics of a substrate word.