Definition of Hydra

1. Noun. (Greek mythology) monster with nine heads; when struck off each head was replaced by two new ones. "Hydra was slain by Hercules"

Category relationships: Greek Mythology
Generic synonyms: Mythical Creature, Mythical Monster

2. Noun. A long faint constellation in the southern hemisphere near the equator stretching between Virgo and Cancer.
Exact synonyms: Snake
Generic synonyms: Constellation

3. Noun. Trouble that cannot be overcome by a single effort because of its many aspects or its persistent and pervasive quality. "We may be facing a hydra that defies any easy solution"
Generic synonyms: Problem, Trouble

4. Noun. Small tubular solitary freshwater hydrozoan polyp.
Generic synonyms: Hydroid, Hydrozoan
Group relationships: Genus Hydra

Definition of Hydra

1. n. 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 terrible monster.

Definition of Hydra

1. Proper noun. (Greek mythology) A mythological serpent with seven heads, slain by Hercules as one of his twelve labours. Also called the Lernaean Hydra. ¹

2. Proper noun. (constellation) A spring constellation of the northern sky, said to resemble a serpent. It lies just south of the zodiac and contains the star Alphard. ¹

3. Proper noun. (astronomy) The name of one of Pluto's moons. (Named 21 June 2006). ¹

4. Noun. Any of several small freshwater polyps of the genus ''Hydra'' and related genera, having a naked cylindrical body and an oral opening surrounded by tentacles. ¹

5. Noun. A complex, multifarious problem or situation that cannot be solved easily and rapidly. ¹

¹ Source:

Definition of Hydra

1. a freshwater polyp [n -DRAS or -DRAE]

Medical Definition of Hydra

1. Genus of freshwater coelenterates (cnidarians). They are small, solitary and only exist in the polyp form, which is a radially symmetrical cylinder that is attached to the substratum at one end and has a mouth surrounded by tentacles at the other. They have considerable powers of regeneration and have been used in studies on positional information in morphogenesis. This entry appears with permission from the Dictionary of Cell and Molecular Biology (11 Mar 2008)

Hydra Pictures

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Lexicographical Neighbors of Hydra

HycI protease
Hydatigera taeniaeformis
Hyde's disease
Hyde Park
Hydnocarpus kurzii
Hydnocarpus laurifolia
Hydnocarpus wightiana
Hydrangea anomala
Hydrangea arborescens
Hydrangea macrophylla hortensis
Hydrangea paniculata
Hydrangea petiolaris
Hydrastis Canadensis
Hydrilla verticillata
Hydrobates pelagicus

Literary usage of Hydra

Below you will find example usage of this term as found in modern and/or classical literature:

1. The American Naturalist by American Society of Naturalists, Essex Institute (1902)
"702), " that a certain ratio exists between the size of a hydra and its number of tentacles, and that when this ratio is destroyed by an increase or ..."

2. Journal of the Royal Microscopical Society by Royal Microscopical Society, London (1878)
"In spite of its abundance, the fresh-water hydra presents a great number of peculiarities insufficiently studied, and particularly ..."

3. Foundations of Biology by Lorande Loss Woodruff (1922)
"B. hydra In discussing the development of animals, it was pointed out that the ... This is well exhibited in hydra, an almost microscopic, fresh-water ..."

4. The Popular Science Monthly by Harry Houdini Collection (Library of Congress) (1888)
"asexual multiplication by buds, and the sign < sexual rep tion by fertilized eggs : ( Feeding hydra, Í Medusa x Medus» Feeding hydra x -j ..."

5. Behavior of the Lower Organisms by Herbert Spencer Jennings (1906)
"LOCOMOTOR REACTIONS IN hydra AND SEA ANEMONES After contracting in response to stimulation, if the stimulus still continues, hydra and the sea anemones ..."

6. A Text-book of Biology for Students in General, Medical and Technical Courses by William Martin Smallwood (1918)
"hydra—AN ANIMAL MADE UP OF TISSUES ONLY. Kinds.—There are two common species of hydra that are abundant in fresh-water streams and ponds. ..."

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