Discussion of accentuation and prosody for forms in -ον, -οι, -ῳ and related diphthongs; examples, place-names, citations (Sappho, Simonides).
ἀρχόμενα ἀπὸ συμφώνου προπερισπᾶται, ζῷον, εὕρηται δὲ καὶ κατὰ διάστασιν παρὰ τῷ Σιμωνίδῃ (fr. 13) οἷον τόδ´ ἡμῖν ἑρπετὸν παρέπτατο, τὸ ζωΐων κάκιστον ἔκτηται βίον. Πτῷον ὄρος, ὅπερ φασὶ κληθῆναι ἀπὸ Πτῴου παιδὸς Ἀκραιφέως καὶ Εὐξίππης ἢ ὅτι Λητὼ ἐκεῖ βουλομένην τεκεῖν κάπρος ἐπιφανεὶς ἐπτόησεν. τὸ μέντοι ᾠόν ὀξύνεται· ἀπὸ φωνήεντος γὰρ ἄρχεται. λέγεται δὲ καὶ ἐν διαλύσει ὤϊον παρὰ τῇ Σαπφοῖ (fr. 56 Bergk), φαῖσι δή ποτα Λήδαν ὑακίνθινον πεπυκαδμένον ὤϊον εὕρην. καὶ ὤεον ἐν πλεονασμῷ τοῦ 'ε'. Τὰ εἰς 'ον' ὑπερδισύλλαβα μονογενῆ τῇ 'οι' διφθόγγῳ παραληγόμενα ἢ τῇ 'ῳ' ταύτην ἔχουσι τὴν διαίρεσιν· προπαροξύνεται μέν, ὅσα σύνθετά ἐστι, ὑπεσταλμένων τῶν ἀπὸ προθέσεως, Ἀκρόθοιον, ᾧ ἠκολούθησε καὶ τὸ Βάλοιον πόλις Μακεδονίας καὶ Μετάχοιον φρούριον Βοιωτίας μεταξὺ Ὀρχομενοῦ καὶ Κορωνείας. Ἔφορος τριακοστῷ. καὶ Σίντοιον φρούριον Ἀρμενίας κτίσμα Γαλατῶν. ἑκατόμβοιον, εἰκοσάβοιον, πεντηκοσάβοιον, ἐννεάβοιον. τὸ δὲ μητρῷον, ἡρῷον, ὑπερῷον προπερισπᾶται, ὥσπερ καὶ τὰ ἀρσενικά. τὸ δὲ περίστῳον προπαροξύνεται· τὸ δὲ προστῷον προπερισπᾶται. καὶ ὤφειλεν ἢ τὰ δύο προπερισπᾶσθαι ἢ τὰ δύο προπαροξύνεσθαι, ἐπειδὴ ἀπὸ τοῦ στοιά ἀμφότερα γέγονεν. ἐνίοτε δὲ τὰ διὰ τοῦ 'ῳον' διὰ ποιητικὴν χρείαν διαλύονται, ὑπερῷον ὑπερώϊον, περίστῳον περιστώϊον, μητρῷον μητρώϊον. Πᾶν οὐδέτερον εἰς 'ον' πρὸ τοῦ 'ο' σύμφωνον ἔχον εἴτε ἁπλοῦν εἴτε σύνθετον, εἰ μὲν δισύλλαβόν ἐστιν, βαρύνεται ἤτοι παροξύνεται καὶ προπερισπᾶται, εἰ δὲ ὑπὲρ δύο συλλαβὰς ὑπάρχει, προπαροξύνεται,
Words beginning with a consonant are circumflexed on the antepenult: ζῷον; and it has also been found with resolution in Simonides (fr. 13), as in: “this creeping thing flew to us, the vilest of living creatures has obtained its life.” Πτῷον is a mountain, which they say was so called either from Πτῷος, son of Ἀκραιφεύς and Εὐξίππη, or because, when Leto wished to give birth there, a boar appeared and frightened her. ᾠόν, however, is acute; for it begins with a vowel. It is also said with resolution ὤϊον in Sappho (fr. 56 Bergk): “they say that once Leda found an egg, hyacinth-colored, thickly covered.” And ὤεον with pleonasm of the ‘ε’. Neuter words in -ον, of more than two syllables, of one gender, having the diphthong ‘οι’ in the penult or having ‘ῳ’, have this division: those that are compounds are accented on the antepenult, with those formed from a preposition excepted—Ἀκρόθοιον; and to it correspond also Βάλοιον, a city of Macedonia, and Μετάχοιον, a fort of Boeotia between Orchomenus and Coroneia. Ephorus in the thirtieth book. Also Σίντοιον, a fort of Armenia, a foundation of the Galatians. ἑκατόμβοιον, εἰκοσάβοιον, πεντηκοσάβοιον, ἐννεάβοιον. But μητρῷον, ἡρῷον, ὑπερῷον are circumflexed on the antepenult, just like the masculines. περίστῳον is accented on the antepenult; but προστῷον is circumflexed on the antepenult. And it ought either that both be circumflexed on the antepenult or that both be accented on the antepenult, since both have come from στοιά. Sometimes, however, the forms in -ῳον are resolved for poetic need: ὑπερῷον → ὑπερώϊον, περίστῳον → περιστώϊον, μητρῷον → μητρώϊον. Every neuter in -ον having a consonant before the ‘ο’, whether simple or compound, if it is disyllabic, is grave—that is, it is either oxytone or circumflexed on the penult; but if it has more than two syllables, it is accented on the antepenult.