Ask at the forum if you have an Ancient or Modern Greek query!

τήν

Ἓν οἶδα, ὅτι οὐδὲν οἶδα –> I know only one thing, that I know nothing | all I know is that I know nothing.
Diogenes Laertius, Lives of the Philosophers, Book 2 sec. 32.

French (Bailly abrégé)

acc. sg. fém. de l’art. ὁ, ἡ, τό;
poét. acc. fém. sg. du pron. relat. ὅς, ἥ, ὅ.

Russian (Dvoretsky)

τήν:
I acc. sing. f к ὁ.
II acc. sing. f к ὅς.