Greek discussion of phonological patterns of suffixes -nos and -os, accent and vowel changes in adjectives and nouns (examples: Κύδνος, στρυφνός, στυγνός, μόρφνος), alternations with υ/ι, and prosodic behavior of monosyllabic/dissyllabic forms.
ἄγνος ἡ βοτάνη καὶ τὰ κύρια, Κύδνος ποταμὸς Κιλικίας, Πύδνος, Κάλυδνος παῖς Οὐρανοῦ, ἀφ´ οὗ Κάλυδνα πόλις Θήβης, ἣ καὶ Κάλυδνος. Τὰ εἰς 'νος' ἁπλᾶ ἔχοντα πρὸ τοῦ 'ν' ἕν τι τῶν ἀντιστοίχων ὀξύνεται, ἐπιθετικὰ ὄντα καὶ μὴ ἔχοντα πρὸ τέλους 'ορ', πυκνός, κραιπνός, τερπνός, στρυφνός—ὁ λόγος τοῦτο διὰ τοῦ 'υ' ἀπαιτεῖ, ὡς γὰρ τέρπω τερπνός, στέγω στεγνός, οὕτω καὶ στύφω στυφνός. καὶ καθάπερ κέντον κέντρον, οὕτω πλεονασμῷ τοῦ 'ρ' στυφνός καὶ στρυφνός, ὅμως εὕρηται καὶ διὰ τοῦ 'ι' προφερόμενον στριφνός. σημειῶδες καὶ τὸ στρυφνός ἐκτεῖνον τὸ 'υ'. Ἀριστοφάνης ἐν Σφηξί (v. 877) παῦσον τ´ αὐτοῦ τοῦτο τὸ λίαν στρυφνόν. Τὰ γὰρ ἄλλα τοιαῦτα τῷ 'υ' παραληγόμενα συνεσταλμένον αὐτὸ ἔχει γυμνός, συχνός, πυκνός, στυγνός—ἰσχνός, θαλπνός, στιλπνός, συχνός, περκνός ὁ μέλας «μόρφνον θηρητῆρ´ ὃν καὶ περκνὸν καλέουσιν» (Ω 316). ὁ μέντοι Ἀρίσταρχος ἀετοῦ εἶδος καὶ βαρύνει, ἀλλ´ ἐπείσθη ἡ παράδοσις τοῖς ὀξύνουσιν. σεσημείωται τὸ λίχνος βαρύτονον ὡς σύνθετον. παρὰ τὸ λίαν χαίνειν. τὸ δὲ μόρφνος ὁ μέλας ἔχει τὸ 'ορ'. τὰ γὰρ εἰς 'ος' λήγοντα δισύλλαβα, μὴ ἔχοντα παρασχηματισμὸν θηλυκοῦ γένους, ἔχοντα πρὸ τέλους τὴν 'ορ' συλλαβὴν πάντα βαρύνεται, ὑπεσταλμένων τῶν εἰς 'μος' ληγόντων οἷον χόρτος, φόρτος, ὅρκος, Ὄρθος τὸ μονογενές, πόρνος, οὐ γὰρ θηλυκὸν αὐτοῦ τὸ πόρνη. οὕτω θέλει καὶ τὸ πτόρθος. οὕτως μόρφνος. παρεφύλαξα δὲ τὰ εἰς 'μος' διὰ τὸ κορμός, φορμός. ἐσχημάτισται δὲ τὸ μόρφνος ἢ παρὰ τὸ μόρφονος ἢ παρὰ τὴν ὄρφνην πλεονάσαντος τοῦ 'μ' κατὰ τὴν ἀρχήν, ἵνα σημαίνηται ὁ μέλας, ἢ παρὰ τὸ μάρπτω μάρφνος ἐστὶ καὶ μόρφνος ὁ συλλαμβάνων, ἐξ οὗ σημαίνεται ὁ ταχύς. καὶ τὸ ὄκνος προσηγορικὸν βαρύνεται. τὰ γὰρ εἰς 'ος' λήγοντα δισύλλαβα μονογενῆ ἀρχόμενα ἀπὸ τοῦ 'ο' καὶ ἔχοντα δύο σύμφωνα ἢ πλείονα βαρύνεσθαι θέλει οἷον ὄμβρος, ὄρρος, ὄσσος, Ὄρθος, ὄγμος. οὕτως καὶ ὄκνος. Τὰ εἰς 'νος' μονογενῆ δισύλλαβα ἔχοντα πρὸ τοῦ 'νος' ἕν τι τῶν ἀντιστοίχων, προηγουμένου φωνήεντος πλὴν τοῦ 'α' βαρύνεται, ὄκνος, κύκνος καὶ Κύκνος ἥρως, Κύθνος ἥρως καὶ νῆσος πρὸς τῇ Δρυοπίδι
ἄγνος, the herb, and the proper names: Κύδνος, a river of Cilicia; Πύδνος; Κάλυδνος, son of Οὐρανός, from whom Κάλυδνα, a city of Thebes, which is also called Κάλυδνος. The simple words in -νος, having before the ν one of the corresponding consonants, are accented on the acute, when they are adjectives and do not have -ορ- before the end: πυκνός, κραιπνός, τερπνός, στρυφνός—the rule requires this through υ; for just as from τέρπω comes τερπνός, and from στέγω στεγνός, so also from στύφω comes στυφνός. And just as κέντον becomes κέντρον, so by pleonasm of ρ there are στυφνός and στρυφνός; yet it is also found pronounced with ι, στριφνός. Noteworthy too is στρυφνός, lengthening the υ. Aristophanes in the Wasps (v. 877): παῦσον τ´ αὐτοῦ τοῦτο τὸ λίαν στρυφνόν. For the other such words, with υ in the penult, have it shortened: γυμνός, συχνός, πυκνός, στυγνός—ἰσχνός, θαλπνός, στιλπνός, συχνός, περκνός, ‘the black’, “μόρφνον θηρητῆρ´ ὃν καὶ περκνὸν καλέουσιν” (Ω 316). Aristarchus, however, takes it as a kind of eagle and gives it the grave accent, but the tradition has been persuaded by those who accent it with the acute. Λίχνος is marked as barytone, as being a compound, from λίαν χαίνειν. But μόρφνος, ‘the black’, has -ορ-. For all disyllables ending in -ος, which have no corresponding feminine formation, and have the syllable -ορ- before the end, are all barytone, with the exception of those ending in -μος, such as χόρτος, φόρτος, ὅρκος, Ὄρθος, the one-gendered, πόρνος—for its feminine is not πόρνη. Thus also πτόρθος is required; thus μόρφνος. I excepted those in -μος because of κορμός, φορμός. And μόρφνος is formed either from μόρφονος, or from ὄρφνη with pleonastic μ at the beginning, so that ‘the black’ may be signified; or from μάρπτω: μάρφνος and μόρφνος mean ‘the one who seizes’, from which ‘swift’ is signified. And ὄκνος, an appellative, is barytone. For disyllables ending in -ος, one-gendered, beginning with ο and having two consonants or more, are required to be barytone, such as ὄμβρος, ὄρρος, ὄσσος, Ὄρθος, ὄγμος; thus also ὄκνος. The one-gendered disyllables in -νος, having before -νος one of the corresponding consonants, with a preceding vowel other than α, are barytone: ὄκνος, κύκνος—and Κύκνος, a hero; Κύθνος, a hero and an island by Dryopis.