• Hydra and the Neighbouring Constellations
    Hydra and the Neighbouring Constellations
  • WordNet 3.6
    • n hydra small tubular solitary freshwater hydrozoan polyp
    • n hydra 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"
    • n Hydra a long faint constellation in the southern hemisphere near the equator stretching between Virgo and Cancer
    • n Hydra (Greek mythology) monster with nine heads; when struck off each head was replaced by two new ones "Hydra was slain by Hercules"
    • ***

Additional illustrations & photos:

Hydra Hydra

Webster's Revised Unabridged Dictionary
  • Interesting fact: The hydra, which is related to the jellyfish, can grow its body back in a couple of days if it is cut in half
    • Hydra (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 terrible monster. "Gorgons, and Hydras , and Chimeras dire."
    • Hydra (Astron) A southern constellation of great length lying southerly from Cancer, Leo, and Virgo.
    • Hydra (Zoöl) Any small fresh-water hydroid of the genus Hydra, usually found attached to sticks, stones, etc., by a basal sucker.
    • Hydra Hence: A multifarious evil, or an evil having many sources; not to be overcome by a single effort.
    • ***
Century Dictionary and Cyclopedia
    • n hydra In Greek myth, a monstrous serpent or dragon of the lake or marsh of Lerna in Argolis, represented as having nine heads, each of which, being cut off, was immediately succeeded by two new ones unless the wound was cauterized. The destruction of this monster was one of the twelve labors of Hercules.
    • n hydra Hence—2. Figuratively, multifarious evil; evil or misfortune arising from many sources and not easily to be surmounted.
    • n hydra [capitalized] An ancient southern constellation, representing a sea-serpent. It is of Babylonian origin, like most of the ancient constellations. It is bounded by the ancient constellations Canis Minor, Argo, Centaurus, Virgo, Corvus, Crater, Leo, and Cancer, and by the modern constellations Sextans and Monoceros (which separates it from Canis Major). It contains one star of the second magnitude, and about four hundred stars visible to the naked eye.
    • n hydra In zoology: A venomous sea-snake; any one of the Hydrophidæ of the Indian ocean.
    • n hydra In Hydrozoa: [capitalized] A genus of fresh-water polyps of very simple structure, typical of the family Hydridæ. Among the species are H. viridis, H. fusca, and H. vulgaris. The body has the form of a cylindrical tube, composed of two fundamental layers, the ectoderm and endoderm, the former containing in one variety green granules identical with the chlorophyl of plants. The base is disk-shaped, and by it the animal can attach itself to any body, being capable of shifting its position. The mouth is surrounded by a circle of extremely contractile tentacles, by which the animal obtains its food, and which are richly endowed with the urticating organs or thread-cells common in the order. The mouth opens immediately into the stomach, and there are no internal organs of any kind, and no anal orifice. Each part of a hydra divided into almost any number of fragments will develop into a fresh independent polypite. Reproduction is effected by gemmation as well as by means of ova and sperm-cells. The genus is said to have been first described by Trembley in 1774, but it is attributed by Agassiz to Linnæus (1756), and the animal was described by A. van Leeuwenhoek in 1703. See cut under Hydrozoa.
    • n hydra An individual or a species of the genus Hydra.
    • n hydra The sexual bud or medusa of any hydroid hydrozoan: so called from its resemblance to a species of the genus Hydra.
    • n hydra A form of self-registering thermometer having a compound head or bulb to contain the spirits, with the object of increasing the surface exposed to the air, and thus making the instrument work with great rapidity.
    • ***
Chambers's Twentieth Century Dictionary
    • n Hydra hī′dra (myth.) a water-serpent with many heads, which when cut off were succeeded by others: any manifold evil: a genus of fresh-water polyps remarkable for their power of multiplication by being cut or divided
    • ***


  • D. H. Lawrence
    “The deadly Hydra now is the hydra of Equality. Liberty, Equality and Fraternity is the three-fanged serpent.”
  • Vivien Kellems
    Vivien Kellems
    “Our tax law is a 1, 598-page hydra-headed monster and I'm going to attack and attack and attack until I have ironed out every fault in it.”


Webster's Revised Unabridged Dictionary
L. hydra, Gr. "y`dra; akin to "y`dwr water. See Otter the animal, Water
Chambers's Twentieth Century Dictionary
L.,—Gr. hydrahydōr, water, akin to Sans. udras, an otter.


In literature:

Describe the parts by which similar excretion is believed to be effected in amoeba, hydra, earthworm, mussel, and lobster.
"Text Book of Biology, Part 1: Vertebrata" by H. G. Wells
Monophysitism is a hydra growth, and no Hercules can be found to exterminate it.
"Monophysitism Past and Present" by A. A. Luce
Enter Hydra, Miss Brilliant & Stage-Keeper.
"The Covent Garden Theatre, or Pasquin Turn'd Drawcansir" by Charles Macklin
It is the hydra of calamities, The sev'nfold death; the jealous are the damn'd.
"The Revenge" by Edward Young
Hope, which is verily a beauteous hydra in the young breast, revived again in strength.
"Cedar Creek" by Elizabeth Hely Walshe
At grips with the hydra of war, Nicolai attacks the evil at the root.
"The Forerunners" by Romain Rolland
The Grand Dragon of the Realm and his eight Hydras.
"Ku Klux Klan" by J. C. Lester
His opponents burned the Greek fleet at Hydra to prevent it falling into his hands.
"The Scrap Book, Volume 1, No. 4" by Various
They grow like the heads of the Hydra.
"Felicitas" by Felix Dahn
But the hydra's body, and its eight other heads, will never do any further mischief.
"A Wonder Book for Girls & Boys" by Nathaniel Hawthorne
The hydra incorporates itself with the man; the man becomes one with the hydra.
"Toilers of the Sea" by Victor Hugo
All this while the hydra-headed mob beneath amuses itself in various ways.
"The Night Side of London" by J. Ewing Ritchie
When tyranny reared its hydra head, the monster was readily recognized.
"Sages and Heroes of the American Revolution" by L. Carroll Judson
The Hydra, raged around, With heads still spouting from the sword I slew.
"Heathen Mythology" by Various
Not by one shaft is Care, the hydra kill'd, So Mirth, determined, had his quiver fill'd.
"The Poetical Works of Sir Edward Bulwer Lytton, Bart. M.P." by Edward Bulwer Lytton
But even if the priests be won over, there remains the people, the hydra-headed; thou knowest not the people.
"John the Baptist: A Play" by Hermann Sudermann
I aimed at the many-headed hydra whose visible representative was Frick.
"Prison Memoirs of an Anarchist" by Alexander Berkman
Here it is as useless as the sword of Hercules against the Hydra.
"The Government of England (Vol. I)" by A. Lawrence Lowell
He perused these papers with all their sensational hydra headed columns, from first to last.
"'£19,000'" by Burford Delannoy
The hydra watched and waited.
"The Life of Bret Harte" by Henry Childs Merwin

In poetry:

Slash on, O Hercules! You may.
Your task's, at best, a Hydra-fray;
And though you cut, not less will grow
More Poets yet!
"More Poets Yet!" by Henry Austin Dobson
Shall augury his goal impart,
Or mind his hidden steps retrace
To mausolean pits of space
Where throbs the Hydra's crimson heart?
"The Testimony of the Suns" by George Sterling
And the Hydra down in the ocean caves
Abode, a creature grim;
And the scaled Serpents huge and strong
Coiled up in the waters dim.
"The Fossil Elephant" by Mary Botham Howitt
The Mammoth huge and the Mastodon
Were buried beneath the earth;
And the Hydra and the Serpents strong,
In the caves where they had birth!
"The Fossil Elephant" by Mary Botham Howitt
"Not ours the Theban's charmed life;
We come not scathless from the strife!
The Python's coil about us clings,
The trampled Hydra bites and stings!
"The Chapel of the Hermits" by John Greenleaf Whittier
Lucifer. Rise, Guliar, Dulciato, and Maltia!
To make the band of enemies complete,
That, like a deadly Hydra, Shall dart against this man
Your seven crests portentous and terrific.
"Adam: A Sacred Drama. Act 1. " by William Cowper

In news:

Hydra Privacy Card Series II.
We write to protest David Brion Davis's misleading review of our book, The Many-Headed Hydra: Sailors, Slaves, Commoners, and the Hidden History of the Revolutionary Atlantic.
The tiny new satellite, temporarily designated P4, is located between the orbits of Nix and Hydra.
One might have guessed from such novels as "The Hydra Head,".
On Hydra, the Pace Is Winning And the Water's Just Fine.
Athens, GA, label the Mylene Sheath has signed a deal with Redeye Distribution, joining a roster of labels that includes Hydra Head, Sargent House, Warp, Barsuk and Thrill Jockey.
David Bar Katz's The Atmosphere of Memory —a Labyrinth production, directed by Pam MacKinnon—is sort of like a theatrical hydra: as soon as one cliché walks offstage, a thousand more spring up in its place.
Boston Victory took a point and saw red twice in two tough road games this week, securing a 1-1 draw away to Seacoast United on Thursday before going down 6-0 at Worcester Hydra on Saturday night.
When the 1956 General Motors cars were introduced in the fall of 1955, they carried with them a new, fully automatic transmission under the already established Hydra-Matic family name.
21' Hydra-Sport walkaround - 200hp Yamaha outboard.
Hydra, a small island just 120 miles from Athens, has become a stronghold of contemporary art.
Mark Borthwick, a Brooklyn artist, plays with the curtain in his installation on Hydra.
Literary drama Eternal Hydra takes on big themes.
John Murphy appears in the play Eternal Hydra, playing at the Firehall Arts Centre through Nov 11.
Bio- Therapeutic 8-ounce Hydra Cleanse.

In science:

The light grey shaded data points show the multi-cavity system Hydra A.
Constraining the Nature of X-ray Cavities in Clusters and Galaxies
Since Hydra A is now the best multi-cavity system with adequate published data to test our models, we have also marked its data points with light grey in Figures 1, 2 and 4.
Constraining the Nature of X-ray Cavities in Clusters and Galaxies
Observations of radial velocity standard stars using WIYN/Hydra showed excellent agreement with published velocities (Paper I).
A Fresh Catch of Massive Binaries in the Cygnus OB2 Association
Given the spectral stability of the fiber-fed Hydra bench-mounted spectrograph, we consider velocities from this instrument to be more reliable.
A Fresh Catch of Massive Binaries in the Cygnus OB2 Association
We prove that Cannon–Thurston maps are well–defined (that is, subgroup inclusion induces a map of the boundaries) for heavily distorted free subgroups inside the family of hyperbolic groups known as hyperbolic hydra.
Cannon-Thurston maps, subgroup distortion, and hyperbolic hydra
Hyperbolic hydra have Cannon–Thurston maps ∂ Λk → ∂ Γk for all k .
Cannon-Thurston maps, subgroup distortion, and hyperbolic hydra
For all k ≥ 2, the modulus of continuity ǫ (δ) for the Cannon–Thurston map ∂ Λk → ∂ Γk for hyperbolic hydra grows at least like 1/n when δ grows like 1/A k (n ).
Cannon-Thurston maps, subgroup distortion, and hyperbolic hydra
The third will allow us to reinterpret Lemma 3.1 (as Corollary 3.3) in a manner well suited to analyzing hyperbolic hydra.
Cannon-Thurston maps, subgroup distortion, and hyperbolic hydra
In this section we will show that Cannon–Thurston maps for hyperbolic hydra are well–defined.
Cannon-Thurston maps, subgroup distortion, and hyperbolic hydra
Recall the map Φ from the hyperbolic hydra group Γk to the hydra group G k defined by a i 7→ a max{1,i } , b j 7→ 1 and t 7→ t for all i , j .
Cannon-Thurston maps, subgroup distortion, and hyperbolic hydra
It is shown that the Hydra groups as well as certain of their generalizations and quotients are, in the main, residually torsion-free nilpotent.
On residual properties of generalized Hydra groups
These Hydra groups are infinite cyclic extensions of finitely generated free groups and so are seemingly closely related to free groups, although their finitely generated subgroups have at most linear distortion.
On residual properties of generalized Hydra groups
The Hydra groups can be viewed as special cases of one-relator groups defined by leftnormed commutators of various weights in disjoint sets of variables.
On residual properties of generalized Hydra groups
There are a number of variations of Theorem 2.1 which involve certain quotients of the Hydra groups, which consist of groups defined by more than a single relation.
On residual properties of generalized Hydra groups
To begin with we will need to prove that the centralizer of the element a in the Hydra group Gk is generated by a.
On residual properties of generalized Hydra groups