ἀμετάπταιστος
From LSJ
Ὁ αὐτὸς ἔφησε τὸν μὲν ὕπνον ὀλιγοχρόνιον θάνατον, τὸν δὲ θάνατον πολυχρόνιον ὕπνον → Plato said that sleep was a short-lived death but death was a long-lived sleep
English (LSJ)
ον,
A infallible, πρόρρησις Gal.17(1).863.
German (Pape)
[Seite 122] dasselbe, eigtl. der nicht straucheln kann, Sp.
Greek (Liddell-Scott)
ἀμετάπταιστος: -ον, μὴ ὑποπίπτων εἰς πταῖσμα, ἀναμάρτητος, Γαλην.