ὦσιν

From LSJ

Κρόνου καὶ Ἰαπετοῦ ἀρχαιότερος → more ancient than Cronos and Iapetus, ante-preadamite, antediluvian

Source

French (Bailly abrégé)

3ᵉ pl. sbj. prés. de εἰμί;
acc. sg. de ὦσις.