ω Ω, ω, ὦ μέγα, twenty-fourth letter of the Gr. alphabet: —as a numeral ωʹ 800, but ͵ω = 800, 000. The name of ὦ μέγα, great or long ο, was given at a later period to distinguish it from ὂ μικρόν little or short ο· but the form Ω was not adopted at Athens till the Archonship of Euclides (B. C. 403); v. sub E, H. Changes of ω, esp. in the dialects: Ionic sometimes for α, as ὤνθρωπος ὤριστος for ἄνθρωπος ἄριστος. Ionic also for αυ, as θῶμα τρῶμα for θαῦμα τραῦμα:—this is also Doric, ὦλαξ for αὖλαξ. Aeolic and Doric ω for ου, as ὠρανός Μῶσα κῶρος λιπῶσα for οὐρανός Μοῦσα κοῦρος λιποῦσα; so, ου and ους in gen. sg. and acc. pl. of 2nd decl. pass into ω and ως. Doric, ω becomes ᾱ, as πρῶτος πρώτιστος θεωρός become πρᾶτος πράτιστος θεᾱρός; so gen. pl. of 1st dec. -ῶν becomes -ᾶν. Aeol. sometimes also υ, as χελύνη for χελώνη.