Polyptoton

Polyptoton /ˌpɒlᵻpˈtoʊtɒn/ is the stylistic scheme in which words derived from the same root are repeated (such as "strong" and "strength"). A related stylistic device is antanaclasis, in which the same word is repeated, but each time with a different sense. Another related term is figura etymologica.

In inflected languages polyptoton is the same word being repeated but appearing each time in a different case. (for example, "Iuppiter," "Iovis," "Iovi," "Iovem," "Iove" [in Latin being the nominative, genitive, dative, accusative, and ablative forms of Iuppiter, respectively]).

The form is relatively common in Latin Christian poetry and prose in a construction called the superlative genitive, in phrases such as sanctum sanctorum ("holy of holies"), and found its way into languages such as Old English, which naturally favored the alliteration that is part and parcel of polyptoton—in fact, polyptoton is "much more prevalent in Old English verse than in Latin verse." The specific superlative genitive in Old English, however, occurs only in Latinate Christian poems, not in secular poetry.