Accent rules for words in -τος and related adjective/noun forms; discussion of accent shifts (βαρεῖα, ὀξύνεται), examples (πλωτός, πρωτός, βρωτός), and conditions affecting accent (number, comparative/superlative, loss of τ, crasis of οα→ω).
ὄνομα κύριον καὶ τὸ ὄρνεον, ᾧ ὁμοίως καὶ τὸ νῶτος ἐπὶ τῆς ψόας. καὶ γὰρ τούτου ἡ χρῆσις, καὶ τὸ μὲν οὐδέτερον πολὺ τὸ νῶτον, ἤδη δὲ καὶ τὸ ἀρσενικόν. ἱστορεῖται δὲ παρὰ Ξενοφῶντι καὶ Ἐφόρῳ. τὸ μέντοι λωτός οὐ κύριον. εἰ μέντοι ἐπιθετικὰ εἴη παραληγόμενα τῷ 'η' ἢ τῷ 'ω', ὀξύνεται, εἰ μὴ ἐπὶ ἀριθμοῦ τάττοιτο, ῥητός, νητός, κμητός, τρητός, οἷς ὅμοιον καὶ τὸ Σητοί ἔθνος καὶ πόλις Βιθυνίας, πλωτός, ἔνθεν «πλωτῇ ἐνὶ νήσῳ» (Od. κ 3), στρωτός, γνωτός, πτωτός, βρωτός, τρωτός, πρωτός ὁ πεπρωμένος, ὅθεν καὶ ἐτόλμησάν τινες ἀναγινώσκειν «ἐπὴν τὰ πρωτὰ γένηται» (Il. Ζ 489), ἵν´ ᾖ τὰ πεπρωμένα, οὐχ ὑγιῶς. πρῶτος δὲ ἐπὶ ἀριθμοῦ. ἰστέον δὲ ὅτι κανόνες κατέσχον τέσσαρες τὴν βαρεῖαν τάσιν· ὡς γὰρ παρὰ τὴν ἐξ γίνεται ἐξώτερος, οὕτως καὶ παρὰ τὴν πρό γέγονε πρότερος συγκριτικὸν καὶ πρότατος ὑπερθετικὸν καὶ ἀποβολῇ τοῦ 'τ' πρόατος καὶ κράσει τοῦ 'οα' εἰς 'ω' πρῶτος· βαρύνεται δὲ ἴσως καὶ ὥσπερ ἐπιμεριζόμενον, μία δὲ ἡ τάσις τῶν ἐπιμεριζομένων ἡ βαρεῖα, ἢ πρὸς ἀντιδιαστολὴν τοῦ πρωτός βαρύνεται. ἔτι δὲ βαρύνεται, ἐπειδὴ τὰ εἰς 'ος' τακτικὰ βαρύνεται, ὑπεσταλμένων τῶν εἰς 'στος', ἕβδομος, ὄγδοος, ἔννατος, δέκατος. Τὰ εἰς 'τος' διβράχεα μονογενῆ βαρύνεται, ὁπότε μὴ ἐπὶ ἀθροίσματος ἢ κύριά εἰσιν ἀπὸ ἐπιθετικῶν ἢ ἔχει ἀντέμφασιν, βάτος, λάτος, βρότος τὸ αἷμα, βροτός δὲ ὁ φθαρτός τὸ τριγενές, πότος τὸ συμπόσιον, ποτός δὲ τὸ πινόμενον, πάτος ἡ ἀναστροφή, Στράτος τὸ μὴ ἐπὶ τοῦ ἀθροίσματος, ἔστι δὲ πόλις Ἀκαρνανίας, στρατός δὲ τὸ σύναγμα, κρότος, κότος, μίτος, νότος, σκότος. τὸ δὲ Κριτός καὶ Κλιτός ὀξύνεται. Τὰ εἰς 'τος' διβράχεα ἐπιθετικὰ μὴ ἐπὶ ἀριθμοῦ ταττόμενα ὀξύνεται,
A proper name, and also the bird, to which likewise belongs νῶτος in the sense of the back upon the ψόα. For there is also the usage of this word: the neuter, for the most part, τὸ νῶτον, and already also the masculine. It is recorded in Xenophon and Ephorus. λωτός, however, is not a proper name. If, however, there are adjectival forms with the penult in 'η' or 'ω', they are accented with an acute, unless they are placed in the category of number: ῥητός, νητός, κμητός, τρητός; and similar to these is also Σητοί, a people and a city of Bithynia; πλωτός, whence “πλωτῇ ἐνὶ νήσῳ” (Od. κ 3); στρωτός, γνωτός, πτωτός, βρωτός, τρωτός; πρωτός, “the fated,” whence some even dared to read “ἐπὴν τὰ πρωτὰ γένηται” (Il. Ζ 489), so that it might mean “the fated things,” not soundly. πρῶτος, however, is used of number. And it must be known that four rules have established the grave accent: for just as from ἐξ comes ἐξώτερος, so also from πρό there has arisen the comparative πρότερος and the superlative πρότατος, and by dropping the 'τ' πρόατος, and by contraction of 'οα' into 'ω' πρῶτος. And it is perhaps given a grave accent also as though it were a form being distributed; and the one accent of distributed forms is the grave; or it is given a grave accent in contrast with πρωτός. Further, it is given a grave accent because the ordinal forms in -ος are given a grave accent, with the exception of those in -στος: ἕβδομος, ὄγδοος, ἔννατος, δέκατος. The disyllabic, single-gender forms in -τος are given a grave accent whenever they are not used of a sum, or are not proper names derived from adjectives, or do not have counter-emphasis: βάτος, λάτος, βρότος “blood,” but βροτός “the perishable one,” the three-gender form; πότος “the drinking-party,” but ποτός “what is drunk”; πάτος “the turning back”; Στράτος, not in the sense of a sum, and it is a city of Acarnania, but στρατός “the gathering”; κρότος, κότος, μίτος, νότος, σκότος. But Κριτός and Κλιτός are accented with an acute. The disyllabic adjectival forms in -τος, when not placed in the category of number, are accented with an acute.