Greek adjectival and ethnicon formation and accentuation (suffix -ιος), examples of proparoxytone/oxytone shifts, dialectal diphthongization in Boeotian (ω/ι → οι)
Θοάντειος, Ἀχίλλειος, Διομήδειος, Ἀριστοφάνειος, Αἰόλειος, Ἰορδάνειος, Αἰσχίνειος, Δημοσθένειος, Ἀριστοτέλειος, Ἀσκληπιάδειος, Τεμμίκειος. Μενέλαος δὲ διὰ τοῦ 'ι' «Τεμμίκιον ἄστυ» ἐν πρώτῳ Θηβαΐδος φησίν. Πελόπειος, Μοψόπειος. θεμίστειος, ἐπιτήδειος. Νυττέρειος. ἔστι δὲ ὄνομα λιμένος. τὸ δὲ ἀδελφειός ἀπὸ τοῦ ἀδελφός πλεονάζει τὸ 'ει' καὶ τὸ Δαρδανειός δὲ ὀξύνεται. τὰ μέντοι προπερισπώμενα μὴ σημαίνοντα μέρος σώματος εὑρεθέντα ταῦτά εἰσι, πρυτανεῖος, ἑταιρεῖος, μεγαλεῖος, γυναικεῖος, ἀκατεῖος. τὸ δὲ ἑταίρειος ἀναλογώτερόν ἐστι προπαροξύνεσθαι, ὡς γὰρ ἡμέτερος ἡμετέρειος κτητικῶς δηλαδὴ καὶ ἀβέλτερος ἀβελτέρειος ὁ μωρός, οὕτω καὶ ἑταίρειος Ζεὺς ὁ ἔφορος τῆς ἐν τῇ ἑταιρίᾳ κοινωνίας. Τὰ εἰς 'οιος' ὑπερδισύλλαβα προπερισπῶνται, εἰ ἐπιθετικὰ εἴη ἢ κύρια, ὁμοφωνοῦντα τοῖς ἐπιθέτοις, ἀλλοῖος, αἰδοῖος, ὁμοῖος, γελοῖος, παντοῖος, ἠοῖος. οἱ δὲ μεταγενέστεροι τῶν Ἀττικῶν τὸ γελοῖος καὶ ὁμοῖος προπαροξύνουσιν. τὸ δὲ φλοιός δισύλλαβον καὶ τὸ κολοιός προσηγορικόν. ὀξύνεται δὲ καὶ τὸ ψοθοιός ὁ ἀκάθαρτος. τὸ δὲ Ζάτοιος, Ἄθοιος κύρια ὄντα προπαροξύνονται, οἷς ὅμοιον καὶ τὸ τραπέζοιος, Βοιωτιακὸν ὄν. οἱ γὰρ Βοιωτοὶ τὸ 'ω' καὶ 'ι' εἰς τὴν 'οι' δίφθογγον τρέπουσι, τὸ πατρώϊος πατροῖος λέγοντες καὶ τὸ ἡρώϊος ἡροῖος.
Thoanteios, Achilleios, Diomēdeios, Aristophaneios, Aiōleios, Iordaneios, Aischineios, Dēmostheneios, Aristoteleios, Asklēpiadeios, Temmikeios. But Menelaus, with ‘ι’, says in the first book of the Thebaid, “Temmikion asty.” Pelopeios, Mopsopeios. themisteios, epitēdeios. Nytter(e)ios: it is the name of a harbor. But adelpheios, from adelphos, has an additional ‘ει’; and Dardaneios too is accented on the acute. Now the words found with circumflex on the antepenult, not signifying a part of the body, are these: prytaneios, hetaireios, megaleios, gynaikeios, akateios. But hetaireios is more in accordance with analogy when accented on the antepenult; for just as hēmeteros yields hēmetereios in the possessive sense, and abelteros yields abeltereios, “the foolish man,” so too hetaireios Zeus, the overseer of the fellowship within the hetairia. Words in -οιος, of more than two syllables, have circumflex on the antepenult, if they are adjectival or proper names, being homophonous with the adjectives: alloios, aidoios, homoios, geloios, pantoios, ēoios. But the later Attic writers accent geloios and homoios on the antepenult. But phloios is disyllabic, and koloios is an appellative. And psothoios, “the unclean,” is also accented on the acute. But Zatoios and Athoios, being proper names, are accented on the antepenult; and similar to them is trapezoios, which is Boeotian. For the Boeotians turn ‘ω’ and ‘ι’ into the diphthong ‘οι’, saying patroios for patrōïos and hēroios for hērōïos.