Hy'drä, n.

noun

n.; Eng. pl. HĪ'DRĀS, Lat. pl. HĪ'DRÆ. [Lat. hydra, Gr. ὕδρα, from ὕδωρ, water.]

(Myth.) A serpent or monster in the lake or marsh of Lerna, in Peloponnesus, represented as having many heads, one of which, being cut off, was immediately succeeded by another, unless the wound was cauterized. It was slain by Hercules.
Hence, a multifarious evil; an evil of many sources or points of action, not to be repressed by a single effort.
(Zoöl.) A minute fresh-water polyp-like animal of the class Medusæ. The body is a simple slender tube, having a mouth-opening at one extremity surrounded by a circle of tentacles. Young hydras bud out from its sides, so that an individual may thus have several heads; and if a head is cut off, another will grow out; or if the body be divided in pieces, each piece will grow into a complete hydra; hence the name hydra, from the old fable.
(Astron.) A southern constellation of great length.