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ου (ὁ) qui préside au mois Μεταγειτνιών ou aux fêtes Μεταγείτνια (Apollon) LYSIM. (HARP.).
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LSJ
ὁ, epith. of Apollo at Athens, Lysim. 21, Suid. s.v. Μεταγειτνιών ; — hence Μεταγειτνιών, ῶνος, ὁ, second month of the Attic year, Antipho 6.44, Arist. HA 549a16, Plu. Publ. 14; also at Delos, IG 11(2).203 A 32 (iii BC), and in Ionic cities, as Priene, SIG 278.2 (iv BC), Miletus, ib. 633.75 (ii BC); cf. Πεδαγείτνιος. (Derived by Gramm. from μετά, γείτων, because people changed their neighbours; gen. sg. written τοῦ Μεταγειτο (abbrev.) IG2². 1672.34.)
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)