One time (ἄπαξ hapaks)

Otherwise, He would need to have suffered repeatedly since the beginning of the world. But now, one time, at the consummation of the ages, He has appeared in order to destroy sin through His own sacrifice. (Heb 9:26)

ἐπεὶ ἔδει αὐτὸν πολλάκις παθεῖν ἀπὸ καταβολῆς κόσμου· νυνὶ δὲ ἅπαξ ἐπὶ συντελείᾳ τῶν αἰώνων εἰς ἀθέτησιν τῆς ἁμαρτίας διὰ τῆς θυσίας αὐτοῦ πεφανέρωται.

alioquin oportebat eum frequenter pati ab origine mundi: nunc autem semel in consummatione sæculorum, ad destitutionem peccati, per hostiam suam apparuit.