Gender Feminine Usage Astronomy, Greek Mythology Scripts Ὕδρα(Ancient Greek) Pronounced Pron. /ˈhaɪ̯.dɹə/(English) Meaning & History Means "water serpent" in Greek, related to ὕδωρ (hydor) meaning "water". In Greek myth this was the name of a many-headed Lernaean serpent slain by Herakles. It is also the name of a northern constellation, as well as a moon of Pluto.