hydra
From LSJ
ὑμῖν ἔξεστι εὐδαίμοσι γενέσθαι → to you it is permitted to be joyful, it is permitted to be happy, it is permitted to be fortunate, vobis licet esse beatis
subs.
P. and V. ὕδρα, ἡ. Proverb., cut off the heads of the Hydra: P. Ὕδραν τέμνειν (Plat., Rep. 426E).