εἰκάς · eikas — LSJ
twentieth day of the month, the last ten days
twentieth day of the month (sc. ἡμέρα), Hes. Op. 792, 820, Plu. Suav. 2.1089c, etc.: pl., B. l.c., Epicur. Fr. 217; ἡ πρώτη, δευτέρα, etc., μετʼ εἰκάδα, εἰκάδας, the 21st, 22nd, etc., Men. 320.3, IG 2(2).890, etc.; τετάρτη ἐπὶ εἰκάδι IG 9(1).694.2 (Corc.): hence εἰκάδες, αἱ, the last ten days of the month, And. 1.121; σελήνην ἄγουσαν εἰκάδας Ar. Nu. 17; τρίτῃ εἰκάδι, i.e. the 23rd, Pl. Lg. 849b.
II
name of the sixth day of the Eleusinian mysteries ( = Boedromion 20), E. Ion 1076 (pl., lyr.), cf. Plu. Phoc. 28.
III
pl., divisions of a tribe, Hsch.