ὀγδό-ᾰτος · ogdo-atos — LSJ
the eighth, the eighth day, octave
the eighth, Il. 19.246, Od. 3.306, Emp. 68 ; ὀ. δεκάς Rev.Phil. 22.357 ; ἡ ὀγδοάτη (sc. ἡμέρα) the eighth day, octave, Hes. Op. 772, 790 (καθʼ ὁγδοάδην δεκάδα prob. in Jahresh. 23 Beibl. 402 (Egypt)).