[{"Bold_text": "noun", "List Items": ["Often Hydra.Classical Mythology.a water or marsh serpent with nine heads, each of which, if cut off, grew back as two; Hercules killed this serpent by cauterizing the necks as he cut off the heads.", "any freshwater polyp of the genus Hydraand related genera, having a cylindrical body with a ring of tentacles surrounding the mouth, and usually living attached to rocks, plants, etc., but also capable of detaching and floating in the water.", "a persistent or many-sided problem that presents new obstacles as soon as one aspect is solved.", "genitive Hydrae[hahy, -dree].(initial capital letter)Astronomy.the Sea Serpent, a large southern constellation extending through 90° of the sky, being the longest of all constellations."]}]