ὀγδόατος

English (LSJ)

η, ον, poet. for ὄγδοος, as τρίτατος for τρίτος,

   A 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 (καθ' ὁγδοάδην δεκάδα prob. in Jahresh.23 Beibl.402 (Egypt)).