Rules of accentuation for disyllabic words ending in -λος and -αυλος, with examples (proper names, place-names, adjectives) and notes on vowel/diphthong behavior.
* Τὰ εἰς 'λος' δισύλλαβα εἴτε κύρια εἴτε προσηγορικὰ τῷ 'ω' παραληγόμενα περισπᾶται, Κῶλος ἔθνος πρὸς τῷ Καυκάσῳ. Ἑκαταῖος Ἀσίᾳ. Σκῶλος πόλις Βοιωτίας. Στῶλος πόλις ἐν Θρᾴκῃ. Τμῶλος, ὃς κατὰ ποιητικὸν μετασχηματισμὸν Τύμωλος. Πῶλος τὸ κύριον καὶ τὸ προσηγορικόν, μῶλος, βῶλος, κῶλος. Χῶλος τὸ κύριον. τὰ δὲ ἐπιθετικὰ ὀξύνεται, χωλός, ψωλός. Τὰ εἰς 'αυλος' δισύλλαβα μονογενῆ μὴ κύρια ὀξύνεται, αὐλός, δαυλός, καυλός, γαυλός ἐπὶ τοῦ ἀγγείου. «γαυλοί τε σκαφίδες» (Od. ι 223), ἐπὶ δὲ τοῦ πλοίου βαρυτόνως. Καλλίμαχος (fr. 217) «Κυπρόθε Σιδόνιός με κατήγαγεν ἐνθάδε γαῦλος». τὸ δὲ Βαῦλος, Παῦλος, Γαῦλος νῆσος πρὸς τῇ Καρχηδόνι. Ἑκαταῖος περιηγήσει—κύρια περισπᾶται καὶ τὸ ναῦλος μὴ ὂν κύριον. τὸ δὲ φαῦλος ἐπίθετον. Τὰ εἰς 'λος' ἐπιθετικὰ ἔχοντα πρὸ τοῦ 'λος' δίφθογγον τὴν διὰ τοῦ 'υ' βαρύνεται οἷον φαῦλος, δοῦλος, οὖλος. τὸ δὲ τραυλός ὀξύνεται καὶ τὸ δαυλός. * Τὸ κοῖλος μόνον εἰς 'λος' λῆγον δισύλλαβον τῇ 'οι' διφθόγγῳ παραληγόμενον βαρύνεται. λέγεται δὲ καὶ κόϊλος. Τὰ εἰς δύο 'λλ' κύρια ἀρσενικὰ βαρύνονται, Ὕλλος υἱὸς Ἡρακλέους, ἀφ´ οὗ Ὑλλεῖς ἔθνος Ἰλλυρικόν, οὓς Ἀπολλόδωρος Ὕλλους γράφει ἐν τῷ περὶ γῆς δευτέρῳ «ὑπὲρ δὲ Ὕλλους Λιβυρνοὶ καί τινες Ἴστροι λεγόμενοι Θρᾷκες». Τέλλος ὁ Ἀθηναῖος Ἡρόδοτος αʹ (c. 30), Μύλλος ποιητὴς κωμικός, Γάλλος ὁ ποταμὸς Φρυγίας· —λέγει δὲ ὁ Πολυίστωρ
The disyllables in -λος, whether proper names or appellatives, with ω in the penult, are circumflexed: Κῶλος, a people by the Caucasus—Hecataeus, in Asia; Σκῶλος, a city of Boeotia; Στῶλος, a city in Thrace; Τμῶλος, which by poetic reshaping is Τύμωλος. Πῶλος, both the proper name and the appellative; likewise μῶλος, βῶλος, κῶλος. Χῶλος is the proper name; but the adjectival forms are accented with an acute, χωλός, ψωλός. The disyllabic simplex words in -αυλος that are not proper names are accented with an acute: αὐλός, δαυλός, καυλός, γαυλός in the sense of the vessel—“γαυλοί τε σκαφίδες” (Od. ι 223); but in the sense of the ship it is barytone. Callimachus (fr. 217): “Κυπρόθε Σιδόνιός με κατήγαγεν ἐνθάδε γαῦλος.” But Βαῦλος, Παῦλος, and Γαῦλος, an island by Carthage—Hecataeus in the Periegesis—are proper names and are circumflexed, as is also ναῦλος, though it is not a proper name; whereas φαῦλος is an adjective. Adjectives in -λος that have before -λος a diphthong of the type with υ are barytone, e.g. φαῦλος, δοῦλος, οὖλος; but τραυλός is accented with an acute, and so is δαυλός.
κοῖλος alone, a disyllable ending in -λος with the diphthong οι in the penult, is barytone; it is also said as κόϊλος. Proper masculine names with double λλ are barytone: Ὕλλος, son of Heracles, from whom the Ὑλλεῖς, an Illyrian people, whom Apollodorus writes as Ὕλλους in the second book of On the Earth: “ὑπὲρ δὲ Ὕλλους Λιβυρνοὶ καί τινες Ἴστροι λεγόμενοι Θρᾷκες.” Τέλλος the Athenian (Herodotus 1 [c. 30]); Μύλλος, a comic poet; Γάλλος, the river of Phrygia;—and Polyhistor says…