πτύξ
πτύξ, ἡ (nom. only Gramm., Hdn.Gr. 1.396, Hsch.), dat. πτῠχί Il. 20.22: pl. πτύχες, πτύχας, 7.247, al., Hes. Sc. 143, etc.: after Hom. πτῠχή, ῆς, which prevails in Pi. (v. infr. II) and Trag.; the metre requires acc. sg. πτύχα in E. Supp. 979 (lyr.), but acc. pl. πτυχάς in S. Fr. 144; in other places either πτύχας or πτυχάς will suit the metre:—