ἀφράστως
From LSJ
Ἓν οἶδα, ὅτι οὐδὲν οἶδα → I know only one thing, that I know nothing | all I know is that I know nothing.
French (Bailly abrégé)
adv.
sans réflexion, à l'improviste.
Étymologie: ἄφραστος.
Russian (Dvoretsky)
ἀφράστως: непредвиденно, неожиданно (ἀ. ἀέλπτως τε Soph.).