Discussion of neuter nouns in -μα and related forms, accentuation patterns (proparoxytone, pre-/post- accent), diphthongs (οι, οἶμα), Aeolic vowel change of medial/postposed ο to υ in ὄνομα/ὄνυμα, examples (ποίημα, ὄνομα, etc.), with brief mention of Euphrates and Rhegma places.
ἐπὶ τῷ Εὐφράτῃ, ὃν Ἀλέξανδρος ζεύξας ἁλύσεσι διεβίβασε τὰ στρατόπεδα. ῥῆγμα καὶ Ῥῆγμα πόλις καὶ κόλπος περὶ τὸν Περσικὸν κόλπον. δῆγμα, δεῖγμα, λῆμμα, τύμμα, οἶμα, ὅπερ ἐστὶ μονῆρες. οὐδὲν γὰρ εἰς 'μα' λῆγον καθαρὸν δισύλλαβον οὐδέτερον πρὸ τέλους ἔχει τὴν 'οι' δίφθογγον, ἀλλὰ μόνον τὸ οἶμα, τὸ γὰρ οἶδμα οὐ καθαρεῦον. δύναται γὰρ καὶ ἀπὸ συμφώνου ἄρχεσθαί τινα ἢ ἀπὸ συμφώνων, ἵνα μή τις λέγῃ, ὅτι ἄλλο οἶμα ἐπιζητῶ. διὸ ἔθηκα πρὸ τέλους. —τὰ δὲ ὑπὲρ δύο συλλαβὰς προπαροξύνεται, ποίημα, ὄρυγμα, τέλεσμα, μελέτημα, βούλημα, εὕρημα. λέγεται καὶ εὕρεμα διὰ τοῦ 'ε'· καί εἰσι μὲν καὶ ἀμφοτέρων χρήσεις, κρείττων δὲ ἡ διὰ τοῦ 'η' ὡς ἀπὸ περισπωμένου τοῦ εὑρῶ, οὗ τὴν περίσπασιν ἐλέγχει ὁ εὑρήσω μέλλων, περιττεύων τοῦ ἐνεστῶτος μιᾷ συλλαβῇ. ὄνομα, ὅ ἐστι μονῆρες. οὐδὲν γὰρ εἰς 'μα' λῆγον οὐδέτερον ἁπλοῦν ἐν ταῖς πρὸ τέλους δύο συλλαβαῖς δισσὸν ἔχει τὸ 'ο', ὡς δῆλον ἐκ τῶν τοιούτων, ποίημα, νόημα, δόνημα, φίλημα, ἀνάθημα, φώνημα, στεφάνωμα, χρύσωμα, κώλυμα, ἔλυμα, ἔρυμα καὶ ἄλλο μυρίον πλῆθος τοιούτων ὀνομάτων ἀδιάπτωτον ποιεῖ τὸν κανόνα. δῆλον ὡς τὸ ὄνομα μονῆρές ἐστι· καὶ γὰρ ἥ τε τρίτη ἀπὸ τέλους τὸ 'ο' ἔχει καὶ ἡ πρὸ τέλους. Αἰολεῖς δὲ ὄνυμα λέγοντες αὐτὸ ἀπολύουσι τοῦ προκειμένου ἐλέγχου. πρόσκειται τῷ κανόνι ἁπλοῦν, ἵνα μή τις ταῦτα σύνθετα ὄντα ὡς ἀντιπίπτοντα παρατάξῃ συνεχῶς ἐν τῇ συνηθείᾳ λεγόμενα, λέγω δὲ τὸ πρόδομα ἢ πρόπομα, ὅπερ καὶ πρόπωμα λέγεται. τούτων οὖν οὕτως ἐχόντων ἄξιόν ἐστι ζητῆσαι, διατί ἐν τῷ ὄνομα οἱ Αἰολεῖς τὸ ἐν τῇ παραληγούσῃ 'ο' ἔτρεψαν εἰς τὸ 'υ' οἷον ὄνυμα καὶ μὴ τὸ ἐν τῇ προπαραληγούσῃ οἷον ὔνομα. Ἔστιν οὖν εἰπεῖν τὰς αἰτίας ταύτας· πρῶτον μὲν ὅτι τὸ ἐν τῇ παραληγούσῃ 'ο' γνήσιόν ἐστιν, ἀπὸ γὰρ τοῦ νέμω γέγονε νόμα καὶ κατὰ πλεονασμὸν τοῦ 'ο' ὄνομα, τὸ δὲ ἐν τῇ ἀρχούσῃ ἀπὸ πλεονασμοῦ ἐστιν. ἄτοπον δέ ἐστι τὸ ἀπὸ πλεονασμοῦ τραπῆναι, ἵνα εὑρεθῶσι δύο πάθη, πλεονασμὸς καὶ τροπή. δεύτερον δὲ ὅτι καὶ ὁ χαρακτὴρ ἀπαιτεῖ τὸ ἐν τῇ παραληγούσῃ 'ο' τραπῆναι. πολλὰ γάρ εἰσιν εἰς 'α' οὐδέτερα διὰ τοῦ 'υμα' ἐκφερόμενα οἷον κώλυμα, ἔρυμα, κῦμα, θῦμα. οὕτως οὖν καὶ ὄνομα. καὶ τούτου χάριν τὸ ἐν τῇ παραληγούσῃ ἐτράπη καὶ οὐ τὸ ἐν τῇ ἀρχούσῃ. Εἰς 'α' μακρὸν ἢ εἰς 'η' ἐπὶ ἑνικῆς εὐθείας ὀνόματος οὐδετέρου οὐκ ἔστιν εὑρεῖν· τὸ γὰρ κάρα ἀπὸ τοῦ κάρανον καὶ τὸ κάρη ἀπὸ τοῦ κάρηνον ἀποκέκοπται. τὸ γὰρ καρή ὀξύτονον θηλυκόν ἐστιν.
At the Euphrates, which Alexander, having bridged with chains, conveyed the armies across. ῥῆγμα and Ῥῆγμα, a city, and a gulf about the Persian Gulf. δῆγμα, δεῖγμα, λῆμμα, τύμμα, οἶμα, which is unique. For no pure disyllabic neuter ending in -μα has the diphthong 'οι' before the final syllable, but only οἶμα; for οἶδμα is not pure. For it is possible for some words to begin with a consonant or with consonants, so that no one may say that I am looking for another οἶμα; therefore I said “before the final syllable.”
But those of more than two syllables are accented with the antepenult: ποίημα, ὄρυγμα, τέλεσμα, μελέτημα, βούλημα, εὕρημα. It is also said εὕρεμα with 'ε'; and there are indeed usages of both, but the form with 'η' is better, as derived from the circumflexed εὑρῶ, whose circumflex is confirmed by the future εὑρήσω, exceeding the present by one syllable.
ὄνομα, which is unique. For no simple neuter ending in -μα has a double 'ο' in the two syllables before the final syllable, as is clear from such forms as ποίημα, νόημα, δόνημα, φίλημα, ἀνάθημα, φώνημα, στεφάνωμα, χρύσωμα, κώλυμα, ἔλυμα, ἔρυμα, and countless other such nouns, which make the rule unexceptionable. It is clear that ὄνομα is unique; for both the third syllable from the end has 'ο' and the syllable before the end. But the Aeolians, saying ὄνυμα, release it from the proposed proof.
The term “simple” is added to the rule, so that no one may set alongside, as counterexamples, those which are compounds and are continually spoken in common usage—I mean πρόδομα or πρόπομα, which is also said πρόπωμα. These matters being so, it is worth inquiring why in ὄνομα the Aeolians changed the 'ο' in the penult into 'υ', as in ὄνυμα, and not the one in the pre-penult, as in ὔνομα.
One may state these reasons: first, that the 'ο' in the penult is genuine—for from νέμω comes νόμα, and by addition of 'ο', ὄνομα—whereas the one in the initial syllable is from addition. And it is absurd for what is from addition to be changed, so that two affections may be found, addition and change. Second, because the form also requires that the 'ο' in the penult be changed. For there are many neuters in -α pronounced with -υμα, such as κώλυμα, ἔρυμα, κῦμα, θῦμα. So too ὄνομα. And for this reason the one in the penult was changed and not the one in the initial syllable.
In -α long or in -η in the nominative singular of a neuter noun it is not possible to find; for κάρα has been cut down from κάρανον and κάρη from κάρηνον. For καρή, with acute accent, is feminine.