Hy"dra (?), n.; pl. E.
Hydras (#), L. Hydræ (#).
[L. hydra, Gr. "y`dra; akin to "y`dwr
water. See Otter the animal, Water.] 1.
(Class. Myth.) A serpent or monster in the lake or marsh
of Lerna, in the Peloponnesus, represented as having many heads, one
of which, when cut off, was immediately succeeded by two others,
unless the wound was cauterized. It was slain by Hercules. Hence, a
Gorgons, and Hydras, and Chimeras
2. Hence: A multifarious evil, or an evil
having many sources; not to be overcome by a single effort.
3. (Zoöl.) Any small fresh-water
hydroid of the genus Hydra, usually found attached to sticks,
stones, etc., by a basal sucker.
☞ The body is a simple tube, having a mouth at one extremity,
surrounded by a circle of tentacles with which it captures its prey.
Young hydras bud out from the sides of the older ones, but soon
become detached and are then like their parent. Hydras are remarkable
for their power of repairing injuries; for if the body be divided in
pieces, each piece will grow into a complete hydra, to which fact the
name alludes. The zooids or hydranths of marine hydroids are
sometimes called hydras.
4. (Astron.) A southern constellation
of great length lying southerly from Cancer, Leo, and