Accent rules for Greek words ending in -μος: which forms become oxytone or barytone depending on preceding consonant (k, t, s, l, r), with notes on proper names and prefixed/attributive forms.
συγκέκοπται εἴτε καὶ ἐντελές ἐστι, δοχμός. τὸ δὲ κρίθμος βαρύνεται εἰς ἰδιότητα. Τὰ εἰς 'μος' ἔχοντα πρὸ τοῦ 'μ' 'κ' σπάνια μέν εἰσι καὶ βαρύνεται οἷον Λάκμος, Δέκμος. τὸ μέντοι Τρωκμός ἔθνος Γαλατικόν— ἐκαλοῦντο δὲ καὶ Τροκμηνοί—ὀξύνεται. Τὰ εἰς 'μος' λήγοντα ἔχοντα πρὸ τοῦ 'μ' τὸ 'τ' βαρύνονται, οἷον πότμος, Πάτμος, Λάτμος. σεσημείωται τὸ ἀτμός ὀξυνόμενον. Τὰ εἰς 'μος' λήγοντα ἁπλᾶ ἔχοντα πρὸ τοῦ 'μ' τὸ 'σ' προσηγορικὰ ὄντα ὀξύνεται, μὴ ἔχοντα ἐν τῇ πρὸ τέλους συλλαβῇ τὸ 'ο' μόνον εἰς 'σ' καταλῆγον, ῥυσμός, δεσμός, δασμός, θεσμός, χρησμός, σπασμός. πρόσκειται «προσηγορικά» ἵνα φύγωμεν τὰ βαρύτονα κύρια τὸ Κροῖσμος καὶ Κάσμος. τὸ δὲ Βρυσμός (ἔστι δὲ ὄνομα βασιλέως) ὀξύνεται. «οὐκ ἔχοντα τὸ 'ο' μόνον». τὸ γὰρ κόσμος βαρύνεται, τὸ δὲ κρουσμός ὀξύνεται. καὶ τὸ σύνδεσμος προπαροξύνεται σύνθετον ὄν. Τὰ εἰς 'μος' προσηγορικὰ ἔχοντα τὴν πρὸ τέλους συλλαβὴν εἰς 'λ' καταλήγουσαν ὀξύνεται, ὀφθαλμός, τιλμός, ψαλμός, παλμός, ἰνδαλμός. τὸ δὲ Ἄλμος τὸ κύριον (ἔστι δὲ πόλις Βοιωτίας, ὡς Ἑλλάνικος· καὶ Σάλμον αὐτήν φησι ἐν δευτέρῳ Δευκαλιωνείας) καὶ τὸ Ὅλμος τὸ κύριον καὶ τὸ προσηγορικὸν βαρύνεται. * Τὰ εἰς 'μος' προσηγορικὰ καὶ ἐπιθετικὰ ἔχοντα τὴν πρὸ τέλους συλλαβὴν εἰς 'ρ' καταλήγουσαν ὀξύνεται, κορμός, φορμός, θερμός. τὸ δὲ ὅρμος βαρύνεται. τὸ δὲ Θέρμος πολίχνιον Αἰτωλίας, ὡς Πολύβιος, καὶ τὸ Σκύρμος πόλις Κυζίκου πλησίον, καὶ Ἕρμοι δῆμος τῆς Ἀκαμαντίδος φυλῆς ὁ καὶ Ἕρμος οὐδετέρως κύρια.
It is syncopated, or else it is complete: δοχμός. But κρίθμος is accented with a grave as a peculiarity. Words in -μος that have κ before μ are rare and are accented with a grave, e.g. Λάκμος, Δέκμος; however Τρωκμός, a Galatian people—they were also called Τροκμηνοί—is accented with an acute. Words ending in -μος that have τ before μ are accented with a grave, e.g. πότμος, Πάτμος, Λάτμος; but ἀτμός is noted as being accented with an acute. Simple appellatives ending in -μος that have σ before μ are accented with an acute, provided that in the penultimate syllable they do not have only ο ending in σ: ῥυσμός, δεσμός, δασμός, θεσμός, χρησμός, σπασμός. “Appellatives” is added so that we may avoid the barytone proper names Κροῖσμος and Κάσμος. But Βρυσμός (it is the name of a king) is accented with an acute. “Not having only ο”: for κόσμος is accented with a grave, but κρουσμός is accented with an acute; and σύνδεσμος is accented on the antepenult, since it is a compound. Appellatives in -μος whose penultimate syllable ends in λ are accented with an acute: ὀφθαλμός, τιλμός, ψαλμός, παλμός, ἰνδαλμός. But the proper name Ἄλμος (it is a city of Boeotia, according to Hellanicus; and in the second book of the Deucalioneia he says it is Σάλμον) and the proper name Ὅλμος and the appellative are accented with a grave. Appellative and adjectival words in -μος whose penultimate syllable ends in ρ are accented with an acute: κορμός, φορμός, θερμός; but ὅρμος is accented with a grave. And Θέρμος, a small town of Aetolia, according to Polybius, and Σκύρμος, a city near Cyzicus, and Ἕρμοι, a deme of the Acamantis tribe, also called Ἕρμος in the neuter, are proper names.