Borrowed from Oscan [Term?], from 𐌐𐌖𐌌𐌐𐌄 (pumpe, “five”) + -eius, from Proto-Italic *kʷenkʷe, from Proto-Indo-European *pénkʷe. Compare Oscan 𐌐𐌞𐌌𐌐𐌀𐌉𐌉𐌀𐌍𐌔 (púmpaiians, “Pompeian”, masc.nom.sg.), which shows that the penultimate vowel was short, as well as the geminate consonant, just as in peius. See also Pompeiī. Doublet of Quinquius, the native Latin form.